The Crossover
by Conejo-sama
Summary: According to Einstein, the universe is limited in time and space. Tadashi Hamada discovers that this idea is not just limited to one universe as he is unexpectedly transported to a world not unlike his own. Unfortunately for him, his arrival attracts the attention of a dangerous foe.
1. Prologue

**HEY! Happy New Year and Happy Valentine's Day! It's been so long, I know, but I have a good reason.**

**Last year, I got a job, and I decided to take a little break from my stories to start on a new project. I've been a member of NANOWRIMO since high school, and the three years I'd participated I never won... until LAST YEAR! If you've read the premise, you have a vague idea of what the story is about, but I want to explain how I came about writing this story.**

**SPOILER ALERT: A year after Big Hero 6 came out, someone by the name of Haruki Ueno came out with a two-issue alternate manga of the movie. In the first volume, Tadashi doesn't die, but instead gets sucked into the wormhole that Callaghan built. I always wondered what happened to him afterwards, and after a few years of dabbling with some ideas, I came up with this! It's a crossover of the movie and the manga (thus the title). I suggest anyone hasn't already read the manga do so, otherwise you might get lost by some of the references. Also, I hadn't seen the Big Hero 6 TV series before writing this, so don't expect to see any of the characters from the show.**

**I've been working on this since November, and after several weeks of editing, I'm finally done! I really hope you all enjoy it!**

**Disclaimer: Obviously I don't own Big Hero 6, but the OCs are all mine.**

* * *

**Big Hero 6: ****The Crossover**

**Prologue**

_"A human being is a part of the whole called by us universe, a part limited in time and space. He experiences himself, his thoughts and feeling as something separated from the rest, a kind of optical delusion of his consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty."_

_Albert Einstein_

**O—O**

There's a certain peace to floating in an endless void; it's almost like a dream. The unknown terror is not as strong when his eyes are closed. The thoughts brewing moments ago—whether or not he'll survive, if he'll ever see his family again, the haunting sounds and images of Hiro reaching out to him as he's sucked into a nebulous void—are mere echoes throughout the passages of time and space.

There's no telling how long he's been floating through this… dimension?

Continuum?

This field of science of is still so new, so _nascent_—everything is indescribable and breathtaking.

It's also scary, nonsensical, and way beyond his depth of understanding.

The scientist in him has a profound curiosity for the unknown. It's part of the reason he agreed to work on this project. The other reason was simple: Abigail. If he could just save one life, it would have been worth it.

But here he is: stranded, hopeless, no Abigail in sight.

Knowing his brother, Hiro will try to find a way to bring him back. Hopefully by then, he won't be a floating pile of bones. As sardonic as these thoughts sound, he still has hope someone will rescue him, and with his loved ones in his thoughts he knows he'll never be forgotten, nor will he forget those waiting for him on the other side. At least he still has his hat…

Wait a minute...

Oh no.

There's nothing there. He reaches for it again. Nope. Still nothing. Just hair. He tries again with this other hand, as if that'll make a difference. Nope. Still just hair. It's gone. The only thing that has any connection to his family, any form of stability that makes sense in this empty, paradoxical plane of existence, is gone. The magnitude of his loss makes it hard to breathe.

Breathing.

Air.

Oh god.

He's floating in an alternate dimension without an air supply; how is he able to breathe?

Now the calm is gone. He opens his eyes and is immediately hit with an overwhelming sensation. There are colors everywhere—yellow, orange, pink, red, blue, chartreuse—but there's nothing solid to grab. Nothing's stable—not without the hat. It's getting harder to breathe, and suddenly the weightlessness grows into a gravity that crushes his skull and wrings the air out of his lungs. He's got nowhere to go, nowhere to stay, nowhere to… what?

What is that?

It's hard to see at first among all the colors, but it's there.

A dot. But as he drifts closer, he realizes it's not just a dot. It's a black dot.

A black hole.

No, not quite. While he's no expert at quantum physics, he knows better than to go near any black holes. As he gets closer, he sees that it's, thankfully, not a subatomic vacuum. It's a wormhole.

A way home.

Home.

The pressure in is lungs is still heavy, but his heart is light and full of hope once again. As he drifts closer to the hole, he almost collides headfirst into a giant piece of debris. The vacuum of the wormhole must have created a field of plaster and scaffolding in result of the disaster of an experiment he and Yokai had tried to create. The space around it is a miscellaneous whorl of colors, creating more colors, new colors, colors he's never seen or thought to ever exist. But as soon as the colors appear, they suddenly bleed out of existence and into the wormhole.

What happens next, he can't recall.


	2. Chapter 1: Just an average Tuesday

**Big Hero 6: ****The Crossover**

**Chapter 1: Just an average Tuesday**

All Aya wanted was a cup of coffee.

That's why she loves Tuesdays; it's the perfect day to get a cup of joe.

To most people, Tuesday is the most boring day of the week. It's definitely not worse than Monday, when the gaggle of students, homemakers, and underpaid minimum-wagers (such as herself) walk through the streets of San Fransokyo like the living dead, putting up with the first work day of the week with Garfield-like enthusiasm, but it's definitely not the weekend, that momentary lapse when you can get away from the nuisances of your weekly routine, whether it's your abusive 20-credit class schedule, the borderline claustrophobic atmosphere of an office that supplies paperclips for other offices, or your annoying coworker Sheila who can't mind her own damn business to save her life.

At the free clinic where Aya works, there are no weekends, and everyone is her Sheila—her coworkers, the patients, everybody. There isn't much gossip to be had, but the working environment is unappealing, all the same. She can deal with hypochondriacs, cokeheads, and families with loud, snot-nosed kids—it's all a part of the job, after all—but her coworkers are a different story. Only three people (including herself) show up on time—none of which are doctors, sadly enough—and even though she's a nurse, she's always assigned to work at the front desk. The doctors are all hubristic assholes who couldn't get internships at real hospitals, and their ringleader just so happens to be the son of man who owns this clinic.

Needless to say, Aya hates her job, but the only thing worse than working with terrible people is working with terrible people without coffee. With a coffee pot full of cigarettes in the staff room and no coffeemaker of her own, Aya's week is a living hell.

But then Tuesday comes around, and Aya's weekend officially begins. By then, the Monday slump is gone, and the rest of the week is on a semi-organized schedule until the weekend comes around. This is especially true of the clinic. The same five people always arrive at the clinic by noon on Tuesday, and the worst of them is only a paper cut. Because she has to work at the clinic full-time, she only has Tuesdays off, and she wouldn't have it any other way. Nothing unexpected ever happens, and Aya can predict the foot traffic of the day so she can arrive hassle-free to her favorite coffee spot: The Lucky Cat Café.

Her friend Nicki introduced her to the place three months ago when she first started her job at the clinic. It had a nice, calm atmosphere, delicious food, and the owner was the nicest, perkiest woman she had ever met. One sip of her signature Lucky Catppuccino, and Aya was immediately hooked. Now every Tuesday, she meets up with Nicki at the Lucky Cat Café to catch up on the happenings of the week, and Aya spends the rest of her day forgetting about that awful clinic.

This Tuesday starts like any other: waking up to the slobbery kisses and doggy breath of her Korean Jindo. She retaliates by flipping him over to the other side of her bed and hugging him, which she knows he hates. "Morning, BaoBao!" Of course, the clock on her nightstand tells her it's a quarter to noon, but she's sure Bao-Bao has been up for hours and has destroyed her kitchen in his desperate search for food, and she's in no rush to clean up that mess. The dog has no perception of time, so he never remembers that Aya only gets up at five in the morning to feed him six out of seven days of the week.

As soon as she gets up, she grabs her phone and reads all twenty messages from Nicki, the last one being a red-faced, frowning emoji. Yikes.

"Nicki?"

"_Where are you!?"_

"Home."

"_What!? Why are you still there?!"_

"Because it's Tuesday."

Aya enters the kitchen, where there are torn up bills and a ripped bag of dog food on the floor, an easy mess compared to some of BaoBao's previous mishaps. At least he didn't pee this time, and now she doesn't have to feed him. She puts her phone on speaker so she can clean up the kitchen.

"_I've been waiting for you for almost two hours!"_

"Outside my apartment?"

"_No! At the hospital!"_

Aya drops her broom, dreading the worst, but in doing so she also scares BaoBao, who had been waiting all morning for his owner to wake up and take him outside. A nice river of his mellow yellow starts to seep toward her fridge. "Shit!" She grabs the entire roll of paper towel, half of which is also torn to shreds and conveniently on the floor, and mops up the one-year-old Jindo's mess before it spreads under the stationary refrigerator.

"_Aya—"_

"What's going on at the hospital? Is my mom okay?"

"_She's fine."_

Aya sighs in relief. "Don't scare me like that."

"_Scare—? Ugh! You already forgot, didn't you?"_

"Forgot what?"

"_I signed you up to help with the blood drive at the hospital. You promised you would do it."_

Aya recalls making no such promise, and she can only assume Nicki asked her before she consumed any coffee.

Aya is just like most Americans; she can't function immediately after she wakes up. The coffeemaker in the clinic was broken the first week she started working there (longest week of her life), so it served as an ashtray for the regular smokers in the building. Even after it was fixed, people continued to put out their cigarettes in the freshly brewed pot. The last thing she needs in addition to her coffee addiction is a fresh cup of nicotine. So now she has to eat her lunch in the bathroom because no one has the decency to go into the alley out back to spare their non-smoking coworkers of that toxic fog, and her only source of caffeine is the cat-themed bistro two miles from her apartment. She owed Nicki so much for introducing her to the Lucky Cat Café.

But caffeine or no caffeine, who in their right mind would commit to do their job on their one day off—_unpaid_ no less? Of course, she can't say that to Nicki; she doesn't have a death wish.

Instead, she just cuts to the chase: "I forgot."

"_AYA!"_

"But I'll be there as soon as I can. I got a couple of errands to run first."

As if reading her mind, Nicki says, _"There's plenty of coffee here!"_

Aya gags in response. Every other coffee drink tastes like garbage juice compared to the Lucky Catppuccino. She says just as much to Nicki.

"_You're impossible."_

"I'll be there in half an hour.

"_You better not be any later than one!"_ With a click, Aya hears nothing but dial tone on the other end of the phone.

Once she finishes cleaning up the mess in the kitchen, Aya gets ready for the rest of the day. She forgoes making breakfast, deciding instead to grab a quick bite while she's getting coffee at the Lucky Cat Café. After brushing her teeth, getting dressed, and wrestling BaoBao into his work vest, Aya is ready to start starting her day.

The first step is a fresh cup of that Lucky Catppuccino.

Loading BaoBao into her old sonata, Aya checks to make sure she has everything she needs—purse, keys, wallet, leash, treats, doggy bags, extra scrubs—before driving out of the parking lot behind her place. She then drives uptown, weaving through a series of rundown apartments and rickety abandoned factories. She would have gone straight up the street into the metropolitan area, but it's already a quarter past noon and she doesn't want to run into lunch rush.

Turning on the radio, Aya lightly taps her fingers on the wheel to the beat of a song that's been playing on this station ten times a day for the past week. Her mouth waters at the thought of biting into a soft, fluffy, hot-out-of-the-oven doughnut. As she turns at the corner, daydreaming about dancing pastries, a figure runs out into the street.

"_HELP!_"

"Holy—!" She stomps on the brake pedal, and BaoBao squeals as he falls on the floor. The stranger is nowhere to be seen. "Oh my gosh…" Jumping out of car, she finds the victim lying on his side, groaning and very much alive. "Oh, thank God! You okay?"

When the young man doesn't immediately answer, Aya rolls him onto his back. As she assesses him for any injuries, she realizes that he's about her age. And very easy on the eyes.

Okay, now's not the time for that, Aya.

"Let's get you off the street." She reaches for his arm, but before she can grab it, he has her in his grasp and nearly pulls her on top of him.

"H-Help… me…" She's alarmed by the desperation in his voice and the fear in his eyes.

"I'm trying, but first you have to help me help you. Can you get up?" He nods and sits up. A bead of red slowly drips down his face. "Oh God, you're bleeding. Um… Hospital! We're going to a hospital."

She takes the arm that has her in a vice-like grip and puts it around her shoulder, heaving him off the ground. But just as soon as they're on their feet, they're back on the ground. "Look out!" He shields her body as a ball of fire shoots over them.

"What the hell was that?!"

"We need to get out of here!"

"But—"

"_Move!_"

Now he's dragging her into the car, her body numb and unresponsive to her own will. She's only aware of the sounds in the background: BaoBao barking in the backseat; the sizzle of the flames eating away at a nearby dumpster; the stranger yelling at her to do something.

"_Drive!_"

Oh yeah. She's in a car.

"Hurry, go!"

She presses on the gas just in time for another fireball to miss them. Her limbs are so rigid and tight she can't let go of the steering wheel nor can she loosen her foot from the gas pedal. She thinks about going straight uptown but then thinks better of it. There are still too many people at this time, and she doubts a crowd will stop whatever is chasing them from firing more blasts. She continues driving through the route she was using to avoid the crowd to try and lose their pursuer. She makes an abrupt U-turn back downtown and parks behind a dumpster in an alley before turning off the engine. "BaoBao, shush!" He stops barking and starts whining. Aya wants to comfort him, but her limbs are still frozen stiff.

They all wait with bated breath until a figure walks—no, _flies_, right past them. Even though she only gets a glimpse, it's good enough to paint a haunting image into her brain: a black wraith completely encased in flames and hidden behind half a kabuki mask, its exposed mouth pulled into a thin line. What has she gotten herself into?

"He's gone." As if those are the magic words, Aya's hands finally let go of the steering wheel. Adrenaline pumps into her blood, and the sound resonates in her ears with a harsh _thump, thump, thump_. Her limps tremble as if she had just been injected with tens shots of espresso. She runs her right hand through BaoBao's short fur, more for her own comfort than his, and practically melts into her seat, resting her other hand over her rapidly beating heart.

"It's okay, BaoBao. Whatever that thing was, it's gone now. You okay, stranger?" Hearing no reply, Aya turns and sees that her new passenger is unconscious. "You've got to be kidding me." She sits there for a minute, contemplating how to handle the situation. She sighs in resolution and disappointment. Coffee will have to wait.

Before she can change her mind, Aya starts the car again and makes her way to the hospital.

* * *

**So, that's it for now! I originally decided to post this once a week, but then I thought that would be too long, especially for a complete story. But there's still a lot of stuff I'm dealing with in my life, and I'd also like to work on completing my other stories. So from now on, I'll be updating this story twice a week. I hope you like my story so far, and remember to _R&R!_**


	3. Chapter 2: Where's my underwear?

**Big Hero 6: ****The Crossover**

**Chapter 2: Where's my underwear?**

The first thing he feels when he wakes up is a lingering, agonizing headache. His mind feels like it's just been through the wringer, and his stomach churns as the unwelcome sensation proliferates his brain. He tries to remember what happened to make his head feel like mashed potatoes, but even thinking about thinking nauseates him. He can't remember anything before waking up here.

Wait a minute…

Where is here?

To prevent himself from blowing chucks, he slowly breathes in through his nose and out his mouth before cautiously opening one eye. The first thing he sees is white. Not a bright white (thank goodness), but even without any light he can tell that the ceiling is colorless, except for a peculiar stain above his head. There's a window on his right, streams of light barely passing through the plastic shudders. Moving further right, he can barely make out a metallic pole with a bag hanging from a loop on the end. An IV bag.

He's in the hospital. How on Earth did he get here?

He hears a low murmur from the other side of the room. He switches eyes to see the door and shadows passing through aperture of light underneath. Next to the door sits a chair, which is currently occupied by a sleeping black and tan dog in a red vest.

"What the…" As soon as he speaks, the dog's ears perk up. He sits up in the chair, tilting his head in an adorable, inquisitive manner. "Um… hi there." Jumping from the chair, the dog joins him on the bed, resting his head and one paw on his chest. For some reason, this immediately calms him down. He didn't even realize how fast his heart was beating a moment ago until the pressure is applied to his chest. He thanks the dog with a scratch behind the ear. "Thanks, buddy."

From behind the door, he hears the click of heels followed by the distant squeak of sneakers on a freshly-mopped floor. The sounds get closer as well as the voices that accompany them.

"So where'd you find this guy again?"

"I didn't find him. He ran in front of my car."

One of those voices sounds familiar but thinking still hurts, so he doesn't bother trying to remember. The dog seems to recognize the voice as well because he jumps off the bed and runs to the door, barking once. The footsteps quicken in pace until a couple of shadows stop outside his door.

"And was that before or after the fire demon showed up?"

"I didn't make it up!"

Fire demon? For some reason, that also sounds familiar.

"I guess I'll just have to get the real story from him."

"Or you can just take my word for it because I'm your friend!"

The door opens to reveal two young women, a doctor and a nurse. The doctor is taller by at least two inches and her chestnut hair is pulled up into a ponytail. She's only wearing navy blue scrubs—most likely an intern—and holding a clipboard. The nurse looks how he feels: exhausted, but at the same time skittish. Her skin is slightly pale, and her midnight brown hair is bedraggled. Her blue puppy-dog scrubs soften the image, but it doesn't completely mitigate the clear, panic-stricken expression on her face. It's like her fight or flight instincts haven't turned off since the incident with Sunfire.

Sunfire… How does he know that name?

"Hey, how're you doing?"

"I… why am I here?"

The doctor's expression shifts from soft concern to blatant worry, and the nurse starts biting her thumbnail. As if sensing her anxiety, the dog paws her leg and whines. She subconsciously pets his head but doesn't look away from her patient.

"You don't remember running into the street? Or getting into my car?"

Once again, he feels an itch at the corner of his mind telling him that he should remember, but he just can't.

"What about the fire demon?"

"Aya, don't—"

"I'm _not_ lying. I know what I saw. Some flying maniac was throwing fire at us! I don't know what the hell it was, but I do know that caffeine definitely had nothing to do with it!"

"Obviously."

A few images suddenly pop into his head—cold limbs, a kabuki mask embroidered in fire, unimaginable colors—and the damn finally breaks. He leans over the side of the bed and vomits.

The women immediately move into action. The doctor helps him sit back up while the nurse puts a glass of water up to his lips. He drinks it ravenously until the nurse pulls it away. "Slowly, or you're just going to throw it all back up again." He does as he's told, savoring the cool, refreshing taste washing away the sourness in his throat.

He pushes her hand away gently. "Sunfire."

"What?"

"That's the man who was chasing us. Sunfire."

"Wait, that was actually a person?"

"Well, he's definitely concussed," says the doctor.

"Oh, just because he actually agrees with me, he must be concussed, right?"

"That, and he has a grade three concussion. Crazy fantasies aside, he needs to stay overnight so we can monitor him. If he loses consciousness again, his condition could be more serious."

"What?" No, he can't stay in one place for long. Sunfire is probably still looking for him. "I can't be here. I have to go."

"You're not going anywhere. There might be serious tissue damage in your brain."

"No, I have to go—I have to!" He's already getting out of bed, careful to slip off the side that doesn't have vomit. "W-Where's my hat?"

"You need to get back in bed."

"See, this is why I don't work without my Lucky Catppuccino."

Catppuccino? Why does _that_ sound familiar? Maybe he should stay in bed.

No, no, no! The longer he stays here, the more danger he'll put everyone in the hospital. "I swear I was wearing a hat. Where are my shoes, and my underwear?"

Finally, the doctor pushes him back onto bed with incredible ease and pins him with a sharp look that gives him the impression that she'd rather break his legs than let him step one foot out of bed. "Sir, you can leave as soon as you've recovered, but you won't recover any faster if you keep moving around. Now, you can either lie in bed like a good little patient, or I can tie you to it." Thoroughly terrorized, he sits back in bed, hugging his knees to his chest like a child in the presence of the Boogey Man. "Good. Aya is going to take down your information. I'll be back to check on you later. Stay. In. Bed." She pierces him with one more serrated glare before leaving.

"You okay?" The nurse, Aya, gives him a gentle smile. She still has a haunted look on her face, but he knows she's trying to appear strong for professionalism's sake.

She's holding dirty paper towels. The reminder of his little accident makes his cheeks glow red in embarrassment. "Sorry about that."

She shrugs nonchalantly. "Just one of the perks of being a nurse. If it makes you feel any better, I've thrown up three times in the past hour."

This actually does make him feel better and finally relaxes against the pillows. "I don't know who's scarier: her or Sunfire."

"Yeah, Nicki can be… intense, but it's only because she cares." Aya hums intriguingly as she grabs the clipboard on the end of his bed. "So… 'Sunfire', huh? Why the hell was this 'Sunfire' chasing you?"

"I… don't remember."

"Do you remember anything before you lost consciousness?"

"I—" The miscellaneous colors from before daub his vision, and the nausea returns.

His face must have given him away because Aya puts a bed pan in his lap. "Just in case."

The blush on his face intensifies. "Sorry. I'm just… Every time I try to remember something, my head hurts, and the only thing I see is colors. The memories are coming back, but very slowly. The only thing I remember so far is Sunfire. And falling. I have no idea why I ended up in that factory, or what he wanted with me."

"Do you at least remember your name?"

"T-Ta… Ta… Something with a 'T'."

"John Doe it is, then." She scribbles it down on the clipboard. "So if you don't remember your own name, can I assume that you don't know your date of birth, either?"

"Yes, you can."

"Or your emergency contact?"

"Nope."

"Perfect."

The dog jumps back onto the bed, tongue lagging. "Hey, buddy. I thought dogs weren't allowed inside the hospital."

"BaoBao's a trained medical assistant and emotional support animal."

That certainly explains how he knew how to calm him down. "'Bao-Bao'?"

"Well, his name is Bao. That's just my nickname for him."

"His nickname is longer than his actual name."

"And you are not the first person to point that out to me." Finishing her last notes, Aya sets the clipboard back on the end of the bed and gets up to leave. "BaoBao will keep you company while I find some clean sheets."

"Wait!" He nearly jumps out of bed to go after her when he remembers Doctor Nicki's threat and leans back into the pillows. "You have to help me get out of here."

Aya sighs as she closes the door, sitting back down next to him. "What are you going to do? Go after this guy? Calling the police is pointless. Leave the superhero work to the superheroes."

"No need to be mean."

"I'm being serious."

"Wait… there really are superheroes here?"

"Where have you been for the past three months?" He gives her a look. "Right. Sorry. San Fransokyo now has its own superhero group, Big Hero 6."

"Big Hero 6? What kind of name is that?"

"There's six of them." He gives her the same look. "I didn't come up with the name. Anyway, you don't need to get involved with this 'Sunfire' anymore. The heroes will take care of it. You're safe."

"It's not that!" He knows trying to convince her is nearly impossible, and the longer he tries the harder his head pounds. He takes a deep breath before explaining himself further. "I may not be able to remember where I come from or how I got into this situation in the first place, but the moment I ran into Sunfire, I've had this feeling..."

"Well, you do have amnesia."

"No, that's not what I meant. It's not just my memories that are missing. I think Sunfire has something to do with whatever's happened to me. It may be dangerous, but I can't just wait around for a bunch of superheroes to save the day. You can either help me, or I'll just sneak out on my own."

He can see the cogs spinning in her mind as she mulls over her options. He's bluffing big time. The doctor's threat lingers in his mind, but so does the terrified look on Aya's face when she first came into the room. She's clearly still traumatized, and she looks like she's going to throw up for the fourth time. BaoBao whimpers next to him, attuned to his owner's distress. He feels guilty about the whole thing. He'd rather not involve her at all if he had the choice, but he's desperate and getting her to cooperate is better than sneaking past that intimidating doctor.

A few minutes pass before she finally releases a long, exasperated breath. "Screw it. Let's go."

"You'll help me?"

"It's not like I work here; I'm just volunteering for the day."

He would have jumped out of bed in joy if he didn't have a concussion. "Thank you!"

"Don't mention it. Now let's get out of here before Nicki comes back and breaks our legs."

"She wouldn't really do that… would she?" This time, Aya gives him a look. "Right. Can you hand me my underwear?"


	4. Chapter 3: What was once impossible

**Big Hero 6: ****The Crossover**

**Chapter 3: What was once impossible**

"Big Hero 6. A force for good. The bane of all evil. The superhero team that San Fransokyo never thought they wanted, but the one they needed—"

"Enough, Fred!" GoGo interrupts the nerd's lengthy monologue as the superheroes makes their way through the newly refurbished Krei Tech building.

It has been three months since Big Hero 6 became public. Three months since they found out the culprit who set the fire during the SFIT showcase was beloved professor and head of the university's robotics program, Professor Robert Callaghan.

Three months since Tadashi's death.

Although his heart is no longer filled with a self-righteous sense of justice turned vengeance, Hiro still can't find himself ever forgiving the former professor. He's glad that Baymax stopped him before he could sully Tadashi's memory. He may never get over get brother's untimely death, but at least he can honor him through his actions. He never intended to form a superhero group with his brother's nerd group at his brother's nerd school in order to do so, but that's what happened. And now he's a member of said nerd group, attending said nerd school, with said superhero group.

In addition to gaining a superhero team, Hiro also gained something he never thought he craved: friends. Being a child prodigy never warranted friends. In fact, it usually did the opposite for little Hiro. Who wants to be friends with the teachers' favorite (not that teachers liked him much, either. No one likes a smarty-pants)? His only use was as a punching bag or as a homework mule. High school was no better. At thirteen, Hiro looked forward to taking advanced classes, but even this proved to be too rudimentary for the young genius. And having a younger, smarter classmate intimidated the other high schoolers, so much so that they avoided him altogether. When Tadashi first introduced him to his "nerd school" friends, Hiro expected the same treatment: derisive glares, upturned noses, condescending remarks about how his age contradicts his intellect. Instead, he was surprised not only by their scientific achievements and Fred's… extensive pop culture knowledge, but also by their convivial personalities, with the exception of GoGo, who shows kindness in more reserved ways. It was the first time Hiro had ever felt like he belonged, and he's grateful every day for Tadashi's meddling ways.

And then there's Baymax. He was the last thing Tadashi ever created, the last mark he left on the world. The giant marshmallow embodies his kindness, his nurturing, and even a little of his stubbornness. Just like Tadashi, Baymax has a habit of helping people even when they don't ask for it. But he isn't just a piece of machinery: as a member of Big Hero 6, he's the team's powerhouse and guardian; to his friends, he's a permanent reminder of their best friend; to Hiro, he's family. And none of them can imagine life without him.

Yep, friends, family, the thrill and excitement of being a superhero—Hiro's got no complaints… except, lately things have become super boring.

It seems like villains are only as evil as the amount of technology they invest into their crime, and none of the criminals they've faced have been as technologically adept as Callaghan. In this month alone, the most lethal thing the team has encountered was a bank robbery, and the guy only had a bat. Lame.

On the plus side, the lack of major criminal activity has made it easier for the college students to catch up on their school work. Tadashi had been right; SFIT is no joke. Bot fighting was child's play compared to all the classes Hiro now has to take, but he wouldn't have it any other way. Each class brings new challenges to the table, and Hiro anticipates tackling every task, mathematical or otherwise.

Today, the team—minus Baymax and sans body armor—is on their way to see the CEO of Krei Tech. After rescuing him and the rest of San Fransokyo from Callaghan's revenge plot, Alistair Krei decided to be their alleged sponsor. So far, the team's work has been low-key, but advertisements for Big Hero 6 started to become commonplace on the billboards of metropolitan San Fransokyo, and on occasion Hiro's seen a few kids passing his street playing with action figures that looked suspiciously like Baymax in his red flight suit. He has no doubt that Krei is profiting off them, but the least he can do is share the profits.

Of course, when they confronted Krei about it, he kindly reminded them that he was not only aware of their secret identities, but he wouldn't hesitate to share this information with whomever was willing to pay for it. Although it didn't sound like much of a threat at first—the only person who could possibly harm them was locked up indefinitely at the San Fransokyo Correctional Facility—they soon realized that, while they were perfectly capable of defending themselves, the same couldn't be said for their friends and families. The last thing Hiro wanted was to put his aunt in harm's way. So Big Hero 6 agreed to Krei's terms (for now), and Krei became their financial benefactor.

Needless to say, Hiro and his friends do not enjoy these circumstances.

On their way to the office, Fred decided to monologue their journey throughout the building. Now that he's living his greatest dream, the comic book guru takes every opportunity to exaggerate their endeavors audibly. Sometimes it's hard to tell if he can differentiate reality from fantasy. At the moment, it's a welcome distraction for all of them. Well, all except GoGo. And Wasabi. Maybe even Honey Lemon.

"Once again, our favorite heroes are summoned to their benefactor, the nefarious Alistair Krei. And while Fred's Angels are content to—"

"We've been over this, Fred," says Wasabi. "We are _not_ going by 'Fred's Angels'!"

"And I am definitely _not_ content," murmurs GoGo. "If you insist on monologuing, the least you can do is be accurate."

"I agree," inputs Honey Lemon meekly. "About Krei summoning us, not the monologuing. If he wants to see us, it's probably not for our benefit."

"I don't think this is just some PR meeting," Hiro says. "If Krei just wanted to exploit us, he wouldn't have summoned us to ask for our permission. Something's up."

During Fred's delusional soliloquy, the young robotics genius had been trying to come up with a plausible reason why Krei would call him—as the designated leader of the troupe, Hiro thought it only right that Krei have his contact info in case of emergencies—and so early in the day. He only said it was important and that the team needed to meet him ASAP. Hiro could only assume it was an emergency.

Soon, the group reaches the office doors. Hiro knocks, the light rap causing an echo in the cavernous hallway. Krei's assistant opens the door for them, and Hiro can see Krei pacing behind his giant bureau.

As soon as he sees the college students, he runs right over to them. "Hiro!" he exclaims in relief, "and friends! I'm so glad you're here."

"Is he ever going to learn our names?" asks Wasabi.

"Probably not," Honey whispers.

"I need your help," continues the billionaire. "Someone stole something from me."

"What else is new?" Hiro mumbles under his breath. Out loud, he asks, "Why didn't you call the police?"

"Well, why call the police when I have my very own team of superheroes?"

"You stole something, didn't you?" GoGo asks bluntly.

"No, of course!" The young woman pops her gum, unconvinced. Out of all five of them, GoGo is the most skeptical, and no one blames her.

In addition to being one of the most successful entrepreneurs in San Fransokyo, Alistair Krei is renowned as a sketchy businessman, never afraid of using shortcuts in order to get his way. But after nearly getting killed by Callaghan, Krei started taking safety protocols more seriously and became a little more sensible about his investments. But none of them are so naïve to believe he completely changed his ways.

After ten seconds of GoGo's blunt glare, the billionaire breaks down. "The apparatus of my teleportation device was stolen last night."

The room is suddenly overcome with an overbearing silence, and not even the pop of GoGo's gum can break it. Hiro has mixed feelings about this discovery. That machine caused him a lot of grief; it's the reason Callaghan is jail, the reason he lost his brother. But it's also partially the reason Big Hero 6 exists and the reason he's now surrounded by a group of courageous friends instead of vindictive peers. The fact that Krei still hasn't dismantled the machine says more about him than the thief, and he can only assume someone stole it for the same reason. He definitely doesn't want a repeat of the Yokai incident, and from the looks on his friends' faces, they agree.

Honestly, the thought of dealing with another high-tech villain excites him.

"We'll find the thief, Mr. Krei," he finally answers. Before he can breathe another word, Krei has him by the shoulders and is leading him and the rest of the team out of his office.

"Thank you so much, Hiro! I'm glad to know I can always depend on you and your friends! My assistant will lead you down to the lab. Thanks so much again!" And with that final word, the business tycoon closes the door, leaving the team in the hands of his very capable assistant.

"Follow me, please." The stern woman leads them back down the hall and into the elevator. She opens a secret compartment of buttons below the regular ones and presses the one on the bottom right.

The ride is silent and awkward and exceedingly long. None of them have ever heard Krei's assistant talk before; they don't even know her name (what kind of pompous jerk doesn't address their assistant by name? Hiro thinks rhetorically). None of them know how to dispel the awkwardness congesting the elevator, so they resort to word-mouthing, shoulder-shrugging, and, Fred's specialty, eyebrow-dancing, in order to communicate without breaking the silence.

A few minutes and a soundless conversation about cheese later, they finally arrive in the "secret" lab. "This way, please." The silence prolongs, with exception to the clicking of heels and the squeaking of sneakers treading across the flawless linoleum floor. They soon reach another secret room, where a few scientists are working. Seeing the new arrivals, the scientists turn their attention to them, making the college students feel even more awkward. "Clear the room." The sharp tone from Krei's assistant is enough to send the scientists scurrying out the room like errant rats. If they have a problem leaving their equipment with a bunch of kids, they don't show it. Once they're alone, BH6 begins their investigation.

It almost feels like they've gone back in time, back on that island in the abandoned lab, where all was revealed: the discovery of the failed experiment, the revelation of Yokai's identity, the blind rage Hiro felt in that moment, taking out Baymax's healthcare chip, the bottomless shame he felt for leaving his friends behind on that island and nearly tainting Tadashi's legacy—

Overall, it's not a good feeling.

"Whoa, guys. Do you realize what this is?" Fred's delusional tirade cuts off his thoughts, and for once Hiro's grateful for it.

"Uh, yeah. Krei already told us," answers GoGo. "Someone stole the portal. That's why we're here, looking for clues."

"There's no need, my super-powered compatriots, for we won't find any clues. This is clearly the work of an anti-hero!"

"An anti-hero?" echoes Honey. "Could you elaborate?"

"Krei's a shrewd businessman; Callaghan probably isn't the only one who has beef with him."

"Then wouldn't that make this another revenge scheme?" Wasabi points out.

"Don't encourage him."

GoGo's warning goes unheeded. Fred is already on a roll. "Think about it! If he simply wanted revenge, why didn't the thief go up to Krei's office and do the deed then? Why did he steal the device instead?" A tangible pause fills the room as everyone ponders on it. So far, Fred's logic is sound. The comic book prodigy takes this as his cue to continue. "And notice how there's barely any damage to the walls, the floor, not even a measly finger print." He brushes his finger over the stainless steel of the wall, licking it. Wasabi grimaces in disgust. "Obviously this was an inside job."

"I think Fred's right," Hiro concurs. "Whoever took the device knew where Krei kept the portal. They knew about the secret lab." The youngest of BH6 checked out all four corners of the room while Fred was postulating. As the comic book enthusiast said, there's no sign anyone has broken in at all. "Only someone with access to this underground facility could have done it." He turns to Krei's assistant. "Who all has access to this facility?"

"Krei and any authorized personnel assigned by Krei."

"So, anyone," GoGo concludes. "Super helpful."

"Do you think we can maybe get a list of the people assigned to work down here?" asks Honey Lemon politely.

"That information is classified."

"Krei really doesn't like making our job easy, does he?"

A light bulb blinks to life in Hiro's mind. "Maybe that's the point…"

"What was that Hiro?"

"Nothing!" He glances over at Krei's assistant, who is stoically watching him and his friends. "You know what, how about we just take a raincheck on this investigation?" Everyone looks at him as if he's lost his marbles. "Finals are next week. I don't know about you guys, but I don't plan on failing my first semester at SFIT just because someone decided to steal from the richest man in San Fransokyo."

His friends continue to stare at him as he heads towards the door. Finally, Fred gasps, having caught on to Hiro's ploy. "Oh, right. 'Finals'. Yeah. Knowledge is power after all, and knowing is just half the—"

"I think they get it, Fred."

GoGo pops her gum and shrugs. "Fine by me."

"Wait, seriously?" Wasabi is flabbergasted as he follows them, but the mention of finals does increase his haste to leave.

Honey Lemon, who is also confused, decides to go along with it. "I mean, Hiro does have a point…"

From the corner of his eye, Hiro spots Krei's assistant on her phone, thankfully indifferent to their sudden departure. Once they're all assembled in the hallway and away from prying eyes and ears, everyone, except Fred, look to the young genius for answers.

"If the thief really is one of Krei's employees, we can't take any chances. It could be anyone."

"Including Krei's assistant." Fred peers around the hallway in suspicion. "No one can be trusted."

"And Krei's not being very forthcoming about the incident," GoGo points out. "He's hiding something."

"So what do we do now?" asks Honey Lemon.

"Even though Hiro was just trying to get us out of the lab, I do like the idea of studying for finals," says Wasabi. "Now that we're done with our final projects, we have more time to study. We have no clues so far, and whoever stole the portal can't use it without a power source. I don't think we have anything to worry about right now."

"Wasabi's right. Studying should take priority right now."

GoGo grimaces at the reminder. "I haven't even looked at Professor Granville's study guide yet. It's ten pages long."

Hiro wants to argue that they shouldn't just set their investigation aside for final exams, but he knows they're right. They may be superheroes, they are SFIT students first.

As the heroes make their way to the elevator, discussing study schedules and, in Fred's case, snacks for late-night cramming and procrastinating, Hiro mentally devises a new plan. Krei is definitely hiding something, but if he's not willing to share what he knows, then there are plenty of other ways to get that information. Finding the thief is another story. One thing's for sure:

There's a new villain in San Fransokyo, and Hiro is totally psyched.

**O—O**

"Dude, wake up."

Hiro swats away the hand poking him. Rubbing his sleep-deprived eyes, the young prodigy can barely make out four figures standing over him. "Oh, morning guys."

"Dude, it's, like, three in the afternoon," Wasabi corrects him.

"You missed all of your classes," says GoGo.

"And free doughnuts!" adds Fred. "Felipe brought them for his birthday." He takes a huge bite into an apple fritter.

"Have you been here all night studying?" Honey Lemon asks in concern.

"Teenagers need approximately nine-and-a-half hours of sleep every night," Baymax comments from his charging station. "Proper rest boosts your immune system, repairs body cells, and helps maintain hormone levels, which is especially important for—"

"Thank you, Baymax! We get it!" Once again, the healthcare companion finds a way to mortify the teen with simple medical facts. "Okay, I might have overdone it last night."

"Yeah, no kidding," says the ever sarcastic GoGo. Looking at the screen of his computer, her dark brown eyes narrow at the content. "This is a list of Krei Tech employees in R&D. You haven't been studying at all, have you?"

"You do realize we have finals in a week, right?" reminds Wasabi.

Hiro smiles sheepishly. "Well, I was planning on studying, but then I happened to find my way to the Krei Tech website instead, and… well, you can guess the rest." Between his initial excitement at the prospect of facing a new villain and the urgent need to find the portal as soon as possible before San Fransokyo is destroyed, Hiro spent the rest of the day doing little else. Studying is the last thing on his mind.

"How'd you get access to this?"

"I… may or may not have hacked into Krei's account."

Honey Lemon looks scandalized. "Hiro!"

"I still haven't found any leads if that makes me look better." From the looks on his friends' faces, it doesn't. "None of the R&D scientists seem like the kind of people who could pull this off. I still gotta do background checks on the rest of Krei's employees and—"

"Okay, that's enough of that." Hiro cries out as GoGo pinches his ear. "Your aunt called us last night. We had to lie for you and tell her that you were studying with us for finals at Fred's house. Now you're going to go home, reassure Cass that you're not dead, and then drop the investigation and sleep."

"Okay, okay! Just let go of my ear!" The older girl does so, and Hiro glares at her as he rubs his tender ear lobe.

"Woman up."

"GoGo's right, Hiro," says Honey. "We know finding the portal is important, but this isn't something you should be doing alone. And you definitely shouldn't be hacking into Krei Tech. We're a team. That means we do this together."

"We're called Big Hero 6 for a reason," adds Wasabi.

"Yeah, and next time you want to snoop, how about letting Fredzilla in the know—ow! Ow!" Fred cries as GoGo pinches his ear.

Hiro finally looks at the collective faces of his friends and teammates. Seeing them worried for him and willing to go along with his plans—though he's partial to Fred when it comes to doing reckless things—makes him even more grateful to Tadashi for introducing them into his life. The thought warms his heart in spite of the ache that comes with thoughts of his deceased brother. "Thanks, guys."

"Come on. We'll take you home." Wasabi pats his shoulder, and Hiro nearly falls out of his chair. He's so exhausted he can barely move. Fred and Honey Lemon help him up before they all walk to parking lot outside the Ito Ishioka Robotics Labs.

A few minutes later, they park a few blocks away from the Lucky Cat Café. Hiro got to nap a little on the ride there, so he has just enough energy to walk back home so he can collapse onto his nice, warm bed. But he has to get past Aunt Cass first.

Dreading the inevitable, Hiro is suddenly astonished by the sight before him. He can't tell if it's sleep-addled brain finally catching up to him or what, but it's real enough to make him stop without warning, causing his friends to bump into each other. "Hiro, what—" GoGo's upbraiding falls flat, and she's clearly noticed it, too. The others soon follow suit as their eyes take in what they never thought possible.

Standing before the front entrance of the Lucky Cat Café are three figures. One is a dog wearing a red vest with a detachable tag on the side that says in big, bold letters, "EMOTIONAL SUPPORT ANIMAL. PLEASE DON'T PET." Behind it is a girl around his friends' age who is taller than GoGo, but shorter than Honey Lemon. She's holding the arm of their main focus. It's someone who'd haunted his dreams for two weeks straight, someone he never thought he'd see again except in photos and videos and the heart of his robot.

Someone they'd buried three months ago.

"Tadashi?"


	5. Chapter 4: A lifetime of memories

**Big Hero 6: ****The Crossover**

**Chapter 4: A lifetime of memories**

She's officially insane.

Aya is not a doctor, but she has two and a half years' worth of medical school curriculum crammed into her head, and she knows enough to diagnose her current situation: utterly and completely insane.

It's not unlike her to do something out of the ordinary for a patient in need, whether it's sneaking a beloved shih tzu into the hospital for an elderly widow or simply buying a soda pop from the vending machine in the hallway for a kid who just got his appendix removed. But helping a patient sneak _out_ of the hospital where she volunteers takes the cake.

By now, John Doe's real nurse will have entered the room with a few painkillers for her patient. After finding the room empty, she will have run off to find Nicki, who will blow a gasket and have a cow at the same time. After summoning the hospital's security, Nicki will have gone looking for Aya, who was the last one to have seen John Doe before returning to the blood drive where she is supposed to be stationed, only to find that her friend/bane of her existence and her dog are also missing. Afterwards, Nicki will have drawn two conclusions: either Aya decided to help their amnestic patient, or he snuck out by himself and Aya is just in the bathroom, cuddling with BaoBao while trying to get over the events that occurred just this afternoon. Right now, Aya wishes she was doing the latter.

"You so owe me a cup of coffee for this."

John Doe hums uncertainly as he searches his pockets for stray change while absentmindedly poking the gauze taped to his temple. "Um… I don't think I have any money."

"Well, as soon as you remember your credit card number, I'll be sure to drag you to the closest ATM. And stop messing with that." She slaps away the hand fingering the bandage.

"Ow! Did medical professionals suddenly become ornery or were they always this way?" John grins puckishly in her periphery. BaoBao barks in the back. To Aya, it sounds suspiciously like laughter.

"Ha, ha."

A red light blinks before the street that leads to her apartment. As they wait in silence, Aya takes the opportunity to observe her current charge. His prior eagerness from their escape at the hospital has left him exhausted, but even the dull bags under his eyes aren't enough to diminish his boyish features. Now that she can really look at him, he doesn't look like a John at all. Although that name is usually reserved for people with no background info, John Doe isn't a suitable name for someone so young. No, she will have to call him something else until he can remember his real name. And she knows she should be focused on more important things—What's going to happen to her when Nicki finally catches on? What's she going to do with not-John Doe? Should she go into work tomorrow or skip? Should she cook or get take-out for dinner tonight?—but thinking about this is much better than thinking about Sunfire and the inevitable qualms she will have to deal with later.

"So, what's the plan, Taro?"

"'Taro'?"

"You said your name started with a 'T' or something. John Doe doesn't suit you, and I can't not call you anything."

"Taro" looks at her like she's the maniac who convinced him to sneak out of the hospital before what looks like understanding flashes across his face. He then averts his gaze to the side, his eyebrows raised slightly as if he's mentally testing out his new name. "Taro it is, then. As for the plan… I have no idea."

"WHAT?!" Aya exclaims, accidentally pressing the brakes in the process. BaoBao yelps as he falls to the floor for the second time that day. She's glad there's no one behind her because she doesn't trust herself to drive safely while having this conversation. "You could have told me that before convincing me to sneak you out!"

"I figured I'd have a better chance of getting more of my memories back if I retraced my steps, and staying cooped up in that hospital wasn't going to help me do that." His dark brown eyes crinkle as he takes on a pained expression, releasing a guttural groan.

"Is your head getting worse?"

"It's not as bad as before, but…" He takes a deep breath through the nose before addressing Aya once more. "I'm sorry I've caused you so much trouble, but you're the only one who's willing to help me right now. I know I'll remember something. I just need more time."

Aya sighs for the umpteenth time that day. It's hard to argue with someone who resembles a wounded puppy. "I'll just add this to your tab."

Taro chuckles. "Deal."

By the time they arrive at her apartment building, he looks ready to collapse. Thankfully he still has the energy to walk, so Aya only has to drag him out of the car. "Okay, handsome. No passing out on me. We just need to get up to my apartment."

"Sorry," he apologizes for the millionth time.

"Stop apologizing. Focus on walking."

A hop, skip, and an elevator ride later, they're inside her apartment. BaoBao closes the door as she deposits Taro onto the couch. "BaoBao, water please." The Jindo obediently trots over to the fridge and struggles to pull the cloth tied to the handle of the refrigerator door. Aya snaps her fingers in Taro's face. "Okay, Taro. Stay with me. You have a grade three concussion, which means no sleeping for twenty-four hours until I'm sure you don't have any brain damage. Now what's the last thing you can remember?"

"… You called me handsome."

Aya rolls her eyes. "Before that! How did we first meet?"

"Sunfire."

"Right, Sunfire. What about him?"

"Sunfire chased me into the street… He wanted me to help with an experiment…"

"Experiment?" He's remembering more. This is a a good sign. "Why would he want you to help him?"

"Something about… interdimensional travel—" He grits his teeth in pain.

"Easy there. Don't try remembering all at once." BaoBao shortly joins them, pushing the water bottle into Aya's leg. "Good boy." She shoves the bottle into Taro's hands. "Drink. _Slowly_."

Taro takes a few sips before continuing. "He was working on something. Yokai needed someone to help him with his research, and I was the only one who was willing to do it."

"I thought his name was Sunfire."

"It is, or it was—I'm not completely sure." He bends over, gingerly cradling his aching head. Aya doesn't understand what he's talking about (interdimensional travel? Did he just come out of a sci-fi movie?), and she hates that she can't help him make sense of the memories he's recovered thus far. The least she can do is help alleviate the pain.

"Hold that thought. I'm gonna find some aspirin."

She goes into the hallway and enters the bathroom. Her medicine cabinet is fully stocked with all the essentials: pain relievers, cold medicine, cough medicine, melatonin—anything that anyone would think they'd need, but for some reason she can't find aspirin or ibuprofen. "Great." The lights flicker on and off before they turn completely off. "Double great. This apartment…"

Heading to her bedroom, she digs through the draw of her nightstand where she usually keeps an extra bottle of stolen ibuprofen packets in her nightstand's drawer (working at the clinic for over 12 hours six out of seven days of the week usually results with a headache at the end of her shifts). She finds a packet in the corner of the drawer, but it's empty, as is the bottle she finds in her purse. Disappointed, Aya returns to the living room, where she finds BaoBao resting his head and on Taro's left knee. He's still holding his head disparagingly.

"Sorry, I can't find any aspirin. I'm gonna need to stop by the pharmacy."

"…I remember studying at SFIT."

"The San Fransokyo Institute of Technology? That SFIT?" He nods. "Well, that's good, isn't it? There's bound to be someone there who recognizes you." There's no reply this time. "Why aren't you happier about this?"

"Something's still doesn't feel right. I don't know what it is, and it's just so… frustrating!" The outburst causes BaoBao to jump up and run into the hallway, most likely to the bedroom. "Sorry."

"I told you to stop apologizing." Aya lies back against the couch. It's not the most comfortable piece of furniture, but after an exhausting day of dealing with paranoid germaphobes and meth-heads, it usually hits the spot. "I understand this is frustrating for you, but this is progress. The fact that you're remembering more so quickly means you probably don't have any cerebral damage. Your memories will make sense eventually."

"Really?"

"Trust me, you are the fastest recovering amnesiac that I've ever met."

"So I'm not your first?"

Aya scoffs. "Of course not. I got a lot of practice when I was studying medicine at the San Fransokyo Medical Institute."

"You're an SFMI student?"

"I said I _studied_ there."

"As in past tense."

"Yep."

"And not right now."

"Nope."

"Why not now?"

"Because of none-ya."

Taro rolls his eyes. "I may have amnesia, but even I know the punchline to that one."

"Then you should also know that I don't share personal information with my patients. Now I have to go to the pharmacy and then get a cup of coffee."

"This late in the afternoon?"

"You heard me. BaoBao!" The Jindo runs back into the room, sitting at his owner's feet expectantly. "Watch him."

"What? I'm not staying here." Taro tries to stand up, but he falls back onto the couch just as quickly.

"Yeah, I don't think so."

"Staying cooped up here is no better than staying cooped up in that hospital. I'm coming with you." Both young adults glare at each other in fixed fortitude. The standoff doesn't last long, though. They're both bone-tired, and Aya comes to her senses as she realizes that a dog, especially a dog as friendly BaoBao, is not going to be enough to stop Taro from leaving her apartment. He has already attached himself to Taro; he's just as much BaoBao's patient as he is Aya's. If anything, the Jindo will most likely help Taro accomplish whatever it is he thinks will help him recover his memories the fastest. And as previously mentioned multiple times, Taro is very much concussed, and he can barely stand on his own. He could hurt himself trying to use the bathroom if she leaves him alone with BaoBao.

Finally breaking eye contact, Aya makes for the door, gesturing for the other two to follow. "If you pass out again, I'm taking you back to the hospital."

Taro smiles victoriously. BaoBao stays by his side as they walk out of the apartment, just as excited as their patient. Aya can't help but shake her head.

Why are boys such idiots?

She drives uptown, this time skipping the scenic route. It's a quarter to four, so the foot traffic should be mild until rush hour. The Lucky Cat Café is closest, so she decides to stop there for a simple to-go latte before heading to the pharmacy. She parks across the street from the coffee and bake shop. The streets are moderately empty, which is good. The last thing a concussed idiot like Taro needs is a busy crowd to navigate through.

But that doesn't seem like much of a problem anymore. While she had been driving, she noticed an abrupt change in Taro. His face was glued to the window, so she couldn't see his expression, nor could she guess what he was thinking.

Now that they're out of the car, Aya watches him as he takes in his new surroundings, studying the streets, the people, the passing vehicles, like a jittery little mouse. If she hadn't just spent the past four hours with him, she would have never guessed that he has a concussion.

"I know this area."

"The technical institute is nearby."

"No, it's not just that. I think… I think I live here." Turning towards the café, Taro stops. He looks at the Lucky Cat for which the eatery is named after sitting over the door. Recognition overtakes his features, and he points at the feline figurine enthusiastically. "That! That's super familiar! How do I know that place?"

"You probably came here a lot. Most college students come here to study."

It's familiar enough to Taro for him to recklessly walk across the street and nearly get run over by a Prius. He keeps walking, ignoring the irate driver and his colorful language, while Aya and BaoBao quickly try to catch up to him before he gets himself killed.

She grabs his arms before he can reach the café door. "Maybe you should stay out here with BaoBao."

"But this place is pet-friendly."

"That's beside the—wait, how do you know that?"

"… I don't know."

"Tadashi?"

The third voice makes all three of them jump out of their skin, but for independent reasons. Aya turns around to see a boy in his early teens along with four others who are closer to her age. The boy is the shortest of their group, and the most recognizable. He's the owner's nephew; she's seen him and his friends inside the coffee shop many times. But that's not the only reason she recognizes him.

Looking back at Taro, she knows he realizes it, too. He and the boy share many of the same features: fair skin, dark brown eyes, raven hair. The younger boy and his friends share varying degrees of shock on their faces, collectively resembling a school of gapping fish. Taro's face, a face so easy to read Aya feels like she knows every chapter cover to back even after only spending four hours with him, is surprisingly blank. When his eyes start to flutter erratically, she's prepared to move.

Everyone immediately rushes towards them as he collapses. His friends repeat his name (Tadashi sounds _way_ better than John or Taro) except for the boy, who is still too shocked to move. He clearly knows who this is. And from his reaction, Taro—_Tadashi_, she quickly corrects herself—clearly knows him, too. But that isn't the only thing she noticed. She's not sure what the others saw before he passed out, but Aya didn't miss the one second when his expression became so full of clarity it looked as if a lifetime of his lost memories literally flashed before his eyes in a spectacular show of color.


	6. Chapter 5: Familiar but different

**Big Hero 6: ****The Crossover**

**Chapter 5: Familiar… but different**

For the third time that day, he wakes up in an unfamiliar place, only this time it doesn't hurt so much. And there's something heavy on his chest. Reaching up, his hand meets something very fuzzy, and, weirdly enough, it's the only thing that's familiar. When he opens his eyes, the light doesn't sting, much to his relief, and the first thing he sees is a wet, black nose.

"BaoBao?" The bark confirms his suspicion, followed by a meow, and the pressure on his chest disappears. He sits up from the couch—his living room couch—and glances around at the other familiar items: the familiar wallpaper, the familiar plants, the familiar pictures of family and friends, the funny paintings and baubles that Aunt Cass likes to put around the apartment—

Aunt Cass. He remembers Aunt Cass. And Mochi. And his friends—GoGo, Wasabi, Honey Lemon, Fred—

Hiro…

He smiles in realization. His memories have returned. He remembers.

Some things are still fuzzy, like what happened before he ran away from Sunfire, or what happened after the showcase at SFIT, but he remembers what's important.

"Welcome back, Taro," a familiar voice says. Aya appears from the kitchen with a mug and a bottle of ibuprofen. "Or should I call you Tadashi?" She gives him a wry smile before handing him the pills. He smells cinnamon and chocolate—his aunt's signature Lucky Catppuccino. Aya grips the mug possessively and looks significantly happier. "You remember anything yet?"

After swallowing two of the pills dry, Tadashi nods. "Yeah, actually."

"Really?"

Another bark comes from the corner of the room, and he turns to see BaoBao and Mochi at play. The Jindo is lying on his back, letting the rotund feline bat at his face. "Mochi?" Hearing his name, the calico turns away from his new playmate and meows. He winds his way around Aya's legs, earning a chin scratch, before jumping onto the young man's lap. He purrs contently, and Tadashi is comforted by the familiar weight. "I missed you, too, buddy."

"What's the last thing you remember?" Aya asks, cautiously hopeful.

"Walking up to the café, seeing my friends and Hiro—" Without warning, he jumps up from the couch, and poor Mochi falls to the floor. He lands elegantly on all fours and hisses at the young man. "Where are they?"

"Calm down. Everyone's downstairs waiting for you to wake up."

"Downstairs?"

"Yeah. We had to drag you all the way upstairs because you passed out. Again." Aya takes a long sip from her mug. When her lips move away from the cat-shaped cup, they hold a sincere smile. "They're extremely worried about you, you know. Especially your little brother."

Little brother. Hiro.

Tadashi feels the pinprick of tears in the corner of his eyes. He has to see him, and he isn't going to wait another second.

He rushes to the stairs, where Aya quickly grabs him before he can descend the first step. "Apparently your memory's still on the fritz because you seem to have forgotten you still have a concussion. You might want to go down those stairs a little more carefully before you end up in the hospital again."

"Oh, right."

She puts her hand in the crook of his arm before taking the lead. Slowly but surely, they climb down the stairs. Tadashi's legs suddenly feel like jelly, and he subconsciously moves his hand from the wall and into the Aya's secure grip. As they get closer to the bottom, he hears familiar voices chattering excitedly.

"—some sort of miracle or something!" He immediately recognizes Honey Lemon's energetic, high-pitched tone.

"It's a revival story! Turns out Tadashi has been the real protagonist the whole time, and now he's come back from the dead to help save the day!" Fred hasn't changed a bit; only he would use superhero tropes as a coping mechanism.

"I mean—this is—it has to—for once Fred is making sense to me and I don't like it!" Wasabi's paranoid voice makes Tadashi chuckle under his breath.

"Woman up." GoGo is as sarcastic as ever, but the deep concern, as well as the distinctive _pop!_ of her bubblegum, is crystal clear.

"Hiro, honey, are you okay?" Aunt Cass's voice is warm and sweet like honey, and it softens the ache in Tadashi's heart.

His brother's silence speaks louder than words. It strengthens his resolve and urges him to reach them faster.

Before he knows it, he's standing in front of the doorway that leads from the café's kitchen to the dining area. The only people in the café are the group of six waiting for him at the table closest to the counter. Noticing the lack of resistance on his arm, he looks back at the stairs where Aya is standing, and she nods encouragingly. He can do this. Taking a deep breath, Tadashi finally goes out to reunite with his friends and family.

Everything quiets down as he walks out from behind the counter. They're all staring at him as if they're seeing a ghost rather than their living, breathing friend, which is a fair reaction. He takes in their faces—Honey's bright, spectacled eyes, GoGo's impassive stare, Wasabi's weepy grin, Fred's fidgety mien—and finally spots the two people sitting next to them. Aunt Cass hasn't aged a day. Her auburn hair is slightly frazzled, but she is ironically the most composed. She's the first to approach him. Her green eyes, the eyes she shares with their late father, examine his entirety with that familiar maternal gaze. When her hands cup his cheeks, the tears he's been holding back finally well over. God, he missed her.

"Aunt Cass..."

The older woman hiccups and pulls the young man into a fierce hug. "Tadashi…" When she pulls away, Tadashi is astonished by the scornful look on her face. "Don't you dare do that again!" He flinches as she pulls him back into another hug. He doesn't remember Aunt Cass being this feisty, but he can't blame her for it. He had disappeared without any warning.

All of a sudden, Tadashi is engulfed in a bundle of arms, and he laughs at the familiar coziness of the group hug. His friends mumble their relief at seeing him again, making jokes and banter, and it feels like he was never gone. Over a few of their heads, he spots Hiro. He's still sitting, refusing to look at the scene. Once the group hug breaks apart, he walks over to his little brother.

"Hiro…?" Warily, he reaches out to put a hand on his shoulder when the teen suddenly ambushes him, knocking them both to the floor. Tadashi's shirt is wet, and Hiro trembles in his arms.

"I th-thought you were d-d-dead… but y-you're here. You're r-really…"

"It's okay, little brother. I'm here now. I'm sorry…" He embraces his brother closer, relishing this moment and never wanting to let him go.

"… Um, I hate to interrupt this incredibly touching moment, but Tar—Tadashi still has a concussion." Aya lingers in the doorway to the kitchen, and her cheeks fill with color when everyone looks at her. BaoBao sits beside her, looking at the group curiously. Tadashi notes the funny looks his friends are giving her. They have always been welcoming towards outsiders, but everyone looks especially deferential towards her. It suddenly dawns on him that while he was unconscious, she's probably talked to his friends and family to discuss his current condition. She's not just a stranger to them anymore; she's their godsend, the reason that Tadashi is in their lives once again.

Aunt Cass is the first to address the nurse. "Thank you so much, Aya!" She pulls the younger woman into a hug (and from the look on Aya's face, this is definitely not the first one she's received today). "If there's any way we can repay you—"

"Your Lucky Catppuccino was enough, thanks."

"Please, I insist! You saved my nephew's life! There must be some way—oh! How about free coffee—for life!"

"That's not necessary, really. I was only doing my job." But he knows it was more than that. Aya didn't have to help him; she could have just let her doctor friend strap him to the bed and simply went on with her day. But, against her better judgement, she helped him break out of a hospital so he could recover his memories, even at the risk of getting in trouble with her doctor friend and running into that fire-flinging psychopath again. He owes her his life.

Tadashi meets her eyes and smiles appreciatively. Aya gives him a tiny grin before breaking eye contact. "A-Anyway, I should be heading out. It was nice meeting you all." Everyone returns the pleasantry, and Cass manages to give her one last squeeze before allowing the young woman and her canine companion to finally leave.

"I meant what I said! Free coffee—anytime you want!"

Aya laughs. "I'll keep that in mind." Tadashi has a feeling she'll be back very soon. But he can't let her leave just yet.

"Aya, wait!" Tadashi follows her and BaoBao outside the café and closes the door so they can talk privately. "I just wanted to personally thank you for all your help."

"Like I said, I was just doing my job."

"We both know that's not true."

Aya rolls her eyes. "Whatever makes you feel better."

A bark interrupts their conversation, and Tadashi kneels down to say goodbye to his other nurse. "Thanks for your help, BaoBao. I'll see ya 'round." He pats the Jindo on the head, earning a few licks. As soon as he gets to his feet, the medical duo makes their way back to Aya's sonata. He turns back to the door when she calls out to him.

"You better not run in front of anymore cars, ya hear!"

Tadashi laughs, "I won't!" and waves to them before heading back inside.

**O—O**

"He did _what?!_ No way!"

"I'm not kidding! Fred nearly flooded the whole biotech department! Class what canceled for a week in order to clean up the mess!"

Tadashi laughs vivaciously at one of the many of his brother and his friends' hijinks.

After Aya and BaoBao left, Hiro and the others bombarded him with so many questions he felt like he was in the Tower of Babel. Aunt Cass soon came to his rescue and kicked them out so Tadashi could rest; he still has a concussion, so the last thing he needs is an interrogation. After his friends all said their goodbyes, Hiro escorted him back upstairs. On the way, Hiro decided to share stories.

Tadashi is glad Hiro was able to turn to his friends in his absence. As a child, Hiro never had any luck making friends, so he has never been open to the idea, especially after high school. Knowing they're hanging out on a regular basis brings tremendous relief to the elder boy. His baby brother is finally growing up.

They finally make it up to their room, where the floor is covered in nothing but paper. "Dude, you couldn't even keep our room clean without my help?"

"Hey, I kept your side clean, didn't I?"

Tadashi moves over to the paper screen dividing their formerly shared room, and just as Hiro said, his side is completely spotless. It almost resembles a shrine in its reverent vacancy. He's sure Hiro hasn't crossed the divider since his disappearance. The only thing that stands out is the hat sitting on his bed. He takes it, puts it on his head, and relishes the familiar feel of it…

Only it doesn't feel familiar at all for some reason. He takes it off and puts it back on the bed casually. He looks around the room some more, taking in all the familiar nooks and crannies, but these seem to be different, too. Perhaps it's all of the junk that's accumulated on Hiro's side since his disappearance, but something doesn't seem right.

"Where's Baymax?"

"I left his battery at the school. I've been doing… research with him all night, and he needed to recharge."

"I see… So, you've really adjusted without me, huh?"

Hiro shrugs uncomfortably. "It's been hard without you, but you were right about the nerds. They're not so bad."

"I told ya so."

"Whatever." Hiro shoves him before sitting on the bed. "Actually, we've been doing some cool projects lately."

Tadashi joins him. "Really? That's awesome, Hiro. What have you guys been working on?"

"Well, the week before I turned in my school application, we—"

"Whoa, whoa, whoa. Back up. Did you apply to a different school?"

Hiro looks at him like he's suddenly grown a third eye. "You're the one who convinced me to go to your nerd school."

"I know, but…" Now Tadashi's confused. He's been attending SFIT with his brother for at least a semester. So what was this about an application?

"You okay, bro?"

"Yeah, I'm just… And when did you first apply to SFIT, again?"

"About a week after the showcase."

The pang of unfamiliarity hits him again. "That can't be right."

"Um, yeah, it is."

"But… that doesn't any make sense! Hiro, we've been together at San Fransokyo Tech for at least a month."

Hiro looks at him like he's crazy. "You must have a serious concussion. I didn't start attending your nerd school until two months ago. Did you hit your head in that fire or something?"

"Fire?"

Tadashi is grasping at straws. Nothing seems familiar anymore, and his brother has become a stranger all of a sudden. What on Earth is going on? "Hiro, how long have I been gone?"

"Almost three months. The semester ends in a week."

Oh God. Has it really been that long?

He looks at the desk for some sort of frame of reference. The clock on Hiro's side confirms the time and the day. Three months exactly.

And next to the clock is Hiro's robot—the one he used to use for bot fighting—the one he used as a frame of reference for his showcase project before dismantling it.

But it's not dismantled.

It's laying against Hiro's computer, very much whole and not a scratch on it.

What the hell is going on?!

"Tadashi?" Hiro looks extremely worried, and the feeling is mutual.

He needs to get out of here. He needs air.

"I-I'll be right back."

He rushes back downstairs before Hiro can reply. He runs past Aunt Cass to get to the bathroom and locks the door. He hears both his aunt and brother calling his name, but he ignores them. He needs to collect his thoughts.

Why did Hiro tell him hadn't admitted into the school until after the semester started when they've spent a month in the same robotics program? Why does he still have the robot when he saw him scrap it to make the microbots? And what was this about a fire? None of this makes any sense!

_Damn it!_ Why can't he remember? Every time he tries, it feels like there's a wall blocking his memories, and if he tries to get an inch past the wall, a drill of pain chisels a hole into his brain. But as much as it hurts, he can't stop now. He needs to know why nothing makes sense. He _needs_ to remember.

And so he pushes. He pushes past the block, past the painstaking throb that drills into his brain and feels like a saw tearing his hippocampus apart. Finally, a crack forms in the wall, and a few memories flood his cerebral cortex.

He remembers the moment when everything changed.

It was the day of the San Fransokyo Technology Showcase. He and Hiro were fighting because the latter was wasting his potential, and he had rejected Professor Callaghan's offer to work in his lab. Tadashi had been so glad that Hiro had an opportunity to help the world with that big brain of his instead of loitering in class and inventing new ways to prank his teachers. He was sure Hiro would take the offer, but no, instead of helping people, the boy genius would rather waste his talents messing around and stay by his big brother's side. So Tadashi told him about his plans of transferring schools and studying welfare. Hiro was outraged, and the brothers broke out into a fight. Tadashi wanted to slap some sense into Hiro, and before he knew it, he actually did. He hit his little brother. It was the first time he'd become physically violent with him, and it made Tadashi feel sick. Hiro stopped talking to him after that.

Later that night, Tadashi received a text message. It was from Professor Callaghan. Months prior, he had recruited the young man to help him with a secret project: to rebuild his teleportation device and rescue his young daughter, Abigail. The message he sent informed Tadashi that he was going to use the machine that night and he needed help with the final adjustments. So the young man snuck out to help. The portal had just been turned on when the silent alarms went off. Someone had found their secret lab. Tadashi watched from the security of the monitoring room when he caught sight of the intruder, and he remembers the sinking feeling in his gut when he saw that it was Hiro.

His little brother.

His precious baby brother, who he'd hurt earlier that day.

He had followed him, and he was on the catwalk, right in front of the portal, which was becoming less stable by the second.

Tadashi ran. He ran faster than he'd thought possible and caught Hiro before he could get sucked in. But just as soon as he'd rescued Hiro, the brothers found their positions reversed. Hiro was too weak to pull him up, so Tadashi did the only thing he could in order to save his brother.

He let go.

_I'm… so proud… of you…_

He remembers saying those words to him before the vacuum of space pulled him away. Hiro can hate him forever, but he had to know those words would always remain true, even if they never saw each other again. He remembers the calm he felt in the nothingness of the other dimension, and then the panic he suffered when he realized he had lost the last link to his home. He remembers the overwhelming colors that clouded his vision, the swirling vortex that led to the other side and, eventually, into the hands of Sunfire. He remembers the black hand of fire reaching out to him, the fear, the desperation to get away, running in front of Aya's car—

And then it hits him.

No wonder everything is so familiar, yet so different at the same time.

None of his memories correlate with Hiro's facts because it's all true. But it's all _wrong_.

His friends, his family—everything is _wrong_.

But it's not just the wrong people, the wrong apartment, or even the wrong city.

It's the wrong universe.


	7. Chapter 6: The missing piece

**Big Hero 6: ****The Crossover**

**Chapter 6: The missing piece**

Before a week ago, there has been no proof that interdimensional travel was a possibility. In all the multiverses that have ever come to be, only one scientist has been able to build a machine that could accomplish such a feat—or perhaps there have been more. Who's to say? The possibilities are endless. But as far as he is aware, he is the _first_ to do it.

His inspiration came from a venerated scientist: Doctor Robert Callaghan, founder of the Laws of Robotics and co-founder of the Callaghan-Catmull spline. But the man wasn't without flaws. While he was an expert in his field, his knowledge still had its limits. He knew the basics of quantum physics, but the mechanics were beyond him. He struggled with the research, sacrificing everything he had in order to find the answers to this unsolvable problem. In the end, he lost everything, including the respect of his admirers.

Callaghan's first mistake was working with that two-faced, miserly fraud, Alistair Krei. As the founding father of robotic laws, he expected better of Callaghan than to rely on someone as shady as Krei to help him with his project. The business tycoon's ideas were so small, so finite, and only served to benefit him lucratively. The opposite could be said for Callaghan. He could only see the big picture, a way for humanity to progress in the future, but his research led him all over the place.

But together, they were able to get onto the right track. What they were working on could have pushed past the boundaries of science. Callaghan and Krei wouldn't just transcend space; they would transcend the space-time continuum itself.

A week before he left, he read about the incident at Krei Tech and Callaghan's meltdown. While he could empathize with former Ph.D., he knew he was bound to fail from the beginning. Callaghan's desperation made him erratic, unsound, and therefore, prone to error. But he wouldn't make the same mistake as Callaghan.

He would succeed because he had nothing to lose.

For months, he prepared his experiment. There were many abandoned factories and warehouses in downtown San Fransokyo, so it didn't take him long to find someplace to start his secret project. He recreated the machine developed by Callaghan and improved upon it. He struggled to surpass the great Doctor Robert Callaghan and in the end, he could proudly say he was on the brink of success. He had everything he needed—the generators, the hadron collider, the portal itself. All he needed to do was test it.

The first one ran smoothly. He could toss anything of reasonable size into the portal and it would come back whole. The second test was less successful. Anything bigger than a lab table would immediately crumble to pieces, destabilizing the portal. It only took him a few hours to make the proper calculations and fix the problem. After the third test, he could put anything inorganic through the portal without any hiccups. Unfortunately, the properties inside the portal's electromagnetic field still weren't stable enough for anything organic to pass through unharmed (as proven when he tossed in a stray rat inside), and whatever adjustments he made to his calculations only lead to further failure.

Something was still missing.

Something that could sustain organic molecules without pulling them apart and trying to put them back together again. Something that could keep the portal from destabilizing and turning his makeshift lab into a giant vacuum.

But what?

He would have to find out later. The electromagnetic field may have been lethal to organic matter, but it was still possible to counteract those forces and shield someone from the dark matter. That was easy enough to overcome, and before he knew it, it was time to do his final test.

As soon as he bypassed the artificial wormhole, time and space became one. He had no idea how long he'd been in the other dimension, but it felt like a millennium. He scolded himself for not thinking of an exit strategy—damn it! He was supposed to be _better_ than Callaghan! Less reckless, more scrupulous, successful…

That's when he saw his saving grace.

A wormhole.

He didn't hesitate pass through and a moment later he landed in a lab that, unfortunately, belonged to the infamous and formerly deceased entrepreneur, Alistair Krei.

But this wasn't the right Krei. Although he wasn't the most scientifically adept, he was no simpleton. And this one was exactly that: simple. That was when he realized he hadn't failed. The portal worked. He had done it!

It seemed fortune did favor the bold.

But he wasn't going to celebrate yet. He may have succeeded where Callaghan had failed, but he hadn't reached his goal just yet. His experiment was still incomplete.

And so he started from scratch. He acquired the necessary materials to get started—materials generously "donated" by Krei himself—and found himself a new lab. He rebuilt the portal and wrote out the correct calculations that led him to his initial success. All he needed was a particle accelerator and—

_Click. Buzz… BOOM!_

And then a boy fell out.

It was the most astounding thing. He hadn't even turned the portal on, but somehow it had magically powered on by itself and birthed a complete stranger into his secret laboratory. The most extraordinary part was that he was still alive. No one should have been able to survive a trip through that dimension so exposed like that. But this boy somehow did. Where had he come from? How long had he been in the other dimension? How had he survived? The only reason he could think it was possible was if…

Yes, of course.

That's what was missing.

Unfortunately, before he could test his theory, the boy disappeared, quite literally. The boy had been within in grasp when he when another hole had appeared under him and swallowed him up. He hadn't gotten far, though. He had flown outside just in time to see an unsuspecting civilian helping the boy off the street. He needed his new test subject back and he couldn't allow any witnesses to get away. Thus began the game of cat and mouse.

He may have lost today, but he would find the missing piece to his success, no matter what it takes.

**O—O**

He waits until it's night to strike. He's already used enough of the suit's energy for the day, and it's useless to him at night. He drives uptown as soon as the work day ends. The streets are clear except for the occasional couple and friend group. It seems that university students still have time to go out, even on school nights.

He parks across the street and sits quietly, letting his machine do all the work.

The drone scuttles over to the building and climbs up to the window of the top floor. The camera magnetically attached to it allows him to see inside the building. Zooming in, he only spots one person occupying the bedroom, and they're fast asleep. It crawls to the next window, where he can see a woman and her cat watching a television program. The window is slightly open, and the bug slips in. He searches the hall, the kitchen, back upstairs where a young boy is sleeping. He lets the drone linger there for a few seconds, nostalgic, before making it go back out into the hall. It seems his search has been for nothing…

Hold on.

The bathroom light is on. A shadow moves back and forth against the wall, creeping from under the crack in the doorjamb. Someone's inside, and they're wide awake. The shadow stops moving, and suddenly he can hear heavy breathing in the background. Whoever's in that bathroom is hyperventilating.

The drone slips under the crack of the door to find a young man squeezed between the toilet and the bathtub. Even with his knees drawn up and his arms hiding his face, he still recognizes the young man who quite literally dropped into his "laboratory".

He's finally found him, the missing piece to his experiment.

But as easy as it would be to retrieve him, he knows now is not the time to act. He'll wait till the woman and boy are gone, and then he'll get his missing piece.

Calling back the drone, he drives off into the night to plot his next course of action.


	8. Chapter 7: What smells like burnt toast?

**Big Hero 6: ****The Crossover**

**Chapter 7: What smells like burnt toast?**

Thirty-six hours.

That's how long Hiro has been awake.

Thirty-six sleepless, caffeine-less hours, not including accidental naps.

Now Hiro can barely focus on the practice test in front of him. But lack of sleep isn't the only reason he can't concentrate this morning.

Tadashi's behavior had been really unusual yesterday. Hiro wants to believe that the concussion is to blame, but he had sensed something off about the oldest Hamada brother since his sudden resurrection.

For one thing, he's alive. As ungrateful as that sounds, especially coming from him, Hiro knows that Tadashi should be dead. He will never forget that heart-stopping moment when his older brother ran into the fire to save Callaghan just seconds before the whole building exploded. There was no chance of him surviving that, not unless he suddenly gained some fire-retardant abilities (side effects may include but are not limited to: memory loss and unintentionally deceiving your loved ones).

Another thing is the conversation they had last night. Hiro had enjoyed catching up with Tadashi, recounting his many shenanigans and reminiscing his first semester of college. He didn't think to tell him about what happened before he officially admitted into SFIT, but he couldn't just omit something like that from his older brother. But the absolute last thing he wanted to do was ruin the moment by mentioning his forming a superhero team so he could unleash all his pent-up anger on the one responsible for his alleged death. Instead, he decided to settle with telling him about Big Hero 6. He doubted his brother would approve of his new life-threatening career choice, but it was better than going to juvie for back-alley bot fighting.

However, before he could even mention BH6, Tadashi started acting weird. For some reason, he thought Hiro was already a student at SFIT. He didn't seem to remember the night he convinced him to give his school a chance or introducing him to his friends. And the reaction he gave when Hiro mentioned the fire was not what he expected. He thought he'd be haunted by the memory, and Hiro regretted bringing it up immediately. But the look he saw on Tadashi's face had nothing to do with the fire. He looked like an animal that had been trapped in an unfamiliar place, and he was desperate to get out. As soon as he set his sights on his old bot, Tadashi jetted out of their room and locked himself in the bathroom. Hiro and Cass tried coaxing him out all night, but he was completely unresponsive. Aunt Cass was three seconds away from calling 9-1-1 when the young man finally told them he was fine and that he just needed some space. In the end, Aunt Cass ended up staying up with Tadashi while Hiro went to bed, the spooked look on his big brother's face plaguing him long into the night.

Needless to say, the teen didn't get much sleep.

"Hiro, are you okay?" asks Honey Lemon. "You look like you haven't sleep in over twenty-four hours."

"You haven't even started on the first problem," adds Wasabi arbitrarily.

The three had decided to study for their finals while Fred and GoGo did some more investigating on the missing portal. Because Hiro had jumpstarted the investigation without them, he was unanimously left out of their plans. The last thing they need is their leader to be on academic probation.

"Yeah, no. I'm fine. It's just… something happened with Tadashi last night."

At the mention of their long-lost friend, the two older college students immediately assault him with questions. Hiro understands they're just concerned about Tadashi and they don't want to lose him when they've only just got him back… but he's _so_ tired and all the lack of sleep is making him cranky. But he refrains himself from losing his temper in the middle of the cafeteria.

It takes them a moment to finally calm down when they plainly see how utterly exhausted Hiro is. Honey Lemon puts a warm hand on top of his and asks more gently, "What happened, Hiro? Is Tadashi alright?"

And so he explains to Wasabi and Honey the events that occurred after they left. "When I woke up this morning, he was still in the bathroom. I have no idea what's going on with him, but… it doesn't feel like I got my brother back at all. It feels like… like it's just a stranger wearing my brother's face."

The two older students exchange a look. Tadashi didn't seem any different to them yesterday. Then again, Cass kicked them out before they even got a chance to talk to him. "Well, he did have a concussion," states Honey.

"You think it got worse?" queries Wasabi. "I mean, not that he can get any worse, but you heard what that nurse said. He could still have a concussion today and we wouldn't even know it! Was he exhibiting any signs last night?"

"What signs?"

"You know, the signs indicative of a concussion: Headache, nausea, dizziness, confusion, memory loss—"

As the bigger young man continues to list the symptoms, Hiro tries to remember if Tadashi had been showing any of those signs yesterday. "Tadashi was really confused," he recalls. "He didn't seem to remember the fire at all, and apparently he thinks I've been at SFIT with him for the past semester."

Honey and Wasabi exchange another, more serious look. "Maybe he should see a doctor."

"Everybody thinks he's dead. How do you think a doctor will react when they see the medical records of my supposedly deceased brother?"

Honey comes up with another solution. "What about Aya?"

"Aya? … Oh yeah!" Hiro will never forget the person who brought his brother back into his life. According to Aya, Tadashi had lost his memories, but he had been quickly regaining them throughout the day and his condition was steadily improving. She told them to call her if something was wrong with Tadashi. This definitely warrants a phone call.

Hiro pulls out his phone and calls his aunt. "_Hiro, hi! What's up?_"

"Hey, Aunt Cass. Aya left you her number, right? Can I have it? I want to ask her something."

"_Oh, um, sure, honey. Hang on a sec..._"

Hiro patiently waits for his aunt to find the number and quickly writes it down once she does. "Thanks, Aunt Cass… Has Tadashi come out yet?"

"_Yeah, he's been out for a while._"

"Is he okay?"

"_He's fine. I'm no doctor, but he's functioning normally, like he doesn't even have a concussion..._" Her voice gets quiet."_He's here now, if you want to talk to him._"

"Um…" Hiro bites his lip. Wasabi and Honey watch him curiously, and he turns around in his seat so they can't see his face. "No, that's okay. I'll just… see him later." He hates the words as he says them, but he knows if he tries talking to Tadashi again, he'll just try to gloss over their awkward discussion from yesterday. He'd rather have that conversation in person.

"_Are you sure?_"

"Yeah, I'm sure. Thanks again, Aunt Cass."

"_Have a good day, sweetie._"

After hanging up, Hiro lets his head fall onto the table. "I'm the worst."

Honey pats his back sympathetically. "No you're not, Hiro. It's understandable how you feel. We all thought Tadashi was gone forever, and now that he's back, it's almost too good to be true."

"Everything's going to be okay," Wasabi reassures him, but he sounds like he's trying to convince himself of that fact. Regardless, it makes Hiro feel a little better.

The _ping!_ of someone's cell phone goes off, thankfully dispersing the uncomfortable vibe encompassing their study table. Wasabi picks up his phone to read his most recent message. "GoGo and Fred found something. They want us to meet up at Fred's place."

Hiro lifts his head, reinvigorated. "Finally!" With superhuman speed, the teen grabs all his study materials, stuffs them into his backpack, and runs out of the cafeteria. He slows down a bit when he realizes that Wasabi's the one with the car, but this doesn't deflate his renewed energy whatsoever. He decides to call Aya later. He's sure if something does happen to Tadashi, Aunt Cass will take care of him.

For now, he just wants to forget that he may not have his brother back and focus on the task ahead.

"Let's catch ourselves a villain."

**O—O**

"Was that Hiro?"

Aunt Cass, who has returned from the kitchen, pockets her cell phone and sits back down on the couch next to Tadashi. "Um, yes, it was. He just had a question."

"Oh… okay."

Cass's smile can't fool him. Hiro didn't want to talk to him, and he can't blame him. Honestly, he doesn't want to talk to Hiro, either. Not until he can figure out how to tell him he's not actually the Tadashi from their world.

Tadashi spent all night trying to comprehend this new revelation. It took several hours of panicking, hyperventilating, rocking on the bathroom floor, and a bout of vomiting, but he finally accepted the reality of his situation. And the reality is this isn't _his_ reality, that wasn't his little brother on the other end on the phone, and as much as he appreciates Cass trying to act like everything's normal, it's definitely not.

"Are you sure you don't want anything to eat, honey?"

Tadashi runs his hands through Mochi's silky-smooth fur. Looking up, he scrutinizes the contours of Cass's face. Physically, he can barely distinguish her from his own aunt, but there are other subtle differences. This Cass is more upbeat, less delicate, and undeniably feistier than his own aunt (the phantom bruise from that powerful hug she gave him yesterday attests to that), but she wears her heart on her sleeve all the same. She may not be his real aunt, but the love she has for him and Hiro is just as palpable.

"I'm okay, really."

"But you haven't eaten since you got home. I'll make you anything you want."

"But the café—"

"Is closed for the day so I can take care of my oldest knuckleheaded nephew. Now, what do you want?"

"No really, I…" His stomach gurgles, disrupting the silence. There's no denying his hunger now.

"Okay, that's it." Cass stands up and stomps back over to the kitchen. "I'm making you something. How's French toast with scrambled eggs sound?"

"It's too late for breakfast, Aunt Cass. It's almost noon."

A loud, dramatic gasp resonates from behind the counter. "I did not just hear my very own nephew say something so blasphemous! It's never too late for breakfast, young man—_Never!_"

Tadashi laughs. Perhaps she's not so different from his real aunt; Cass would never let him start the day without breakfast, no matter what time it was. "Alright, French toast it is." He sets Mochi on the couch before joining her in the kitchen. "Here, let me help you."

Despite the circumstances, he takes delight in the familiarity of this scene: helping Cass make breakfast, sneaking tastes and avoiding a whack from her wooden spoon, whistling showtunes while cleaning the dishes. This is one of the things he thought he would never get to experience again, and he's glad he can do it once more, even if it's with the wrong person.

The first few weeks after their parents died were hard on everyone, especially Aunt Cass. While he and Hiro had lost their parents, Cass had lost a sibling, and she had suddenly been trusted with the responsibility of taking care of two young lives. So at the age of ten, Tadashi stepped up not only as a caring older brother, but also as a reliable nephew. He cheered Cass up, helped her with chores in the apartment and, once he was old enough, in the café, and he even took care of her when she was sick. Tragedy may have brought them all together, but the effort he made with his family strengthened the bond between him and Cass.

It makes him miss home even more.

"So… you want to talk about what happened between you and Hiro yesterday?"

Tadashi scrapes his fork across his plate reservedly. He'd barely touched his eggs, but there's no trace of his French toast. He has little appetite now that Cass is now bringing up the reason he holed himself up in the bathroom last night; he's not even sure if he can keep down what he just ate. Now that he knows the truth, he's not sure how to go about answering her. Before he can explain, he needs to know what happened to him—to _their_ Tadashi.

"Aunt Cass, can I ask you something?"

"Sure, honey. Ask away."

"What happened… the night I disappeared?"

Cass drops her fork, which clangs against her plate. She quickly reaches out to catch it only to knock over her glass, spilling orange over the edge of the table and onto the floor. "Oh, jeez!"

Tadashi makes for the paper towel and kneels to help his not aunt clean up the mess. "Sorry, I didn't mean—"

"No, no, it's okay. It's just…" Cass stops wiping the floor and brings a hand to her mouth. A silent tear falls down her cheek.

"Aunt Cass…"

"I-I'm sorry. It's just… you've been gone for three months… Me and Hiro… w-we were finally getting used to the idea… of never seeing you again…"

Tadashi pulls her into a hug. "I'm sorry, Aunt Cass. I'm so, so sorry…"

He doesn't need to know what happened. This family has suffered enough, and he can only imagine how his family is handling his absence. The guilt claws on his insides the longer she cries. Whether he's her Tadashi or not, he caused her this pain. And as much as it hurts them both, he'll have to do it again.

He can't stay in this reality, not as long as there's a chance that their Tadashi could still be alive.

After a few more minutes of silent weeping and warm embracing, Aunt Cass lets him go. "_Woo!_ Well, that was—*ahem*—that was a downer. I haven't cried like that in… three months!" She takes another deep breath before getting up from the floor. "I have to mop this up before the floor gets all sticky."

"I can help."

"Nope! You're supposed to be taking it easy. Now go into the other room while I clean up the mess I made."

Tadashi doesn't argue and joins Mochi on the couch once again. The fat feline jumps on his lap, purring up a storm. A second later, he hisses and runs into the hall. The peculiar smell of burnt toast drifts into his nose. "Aunt Cass, do you still have something in the toaster?"

"I don't believe so."

The smell gets stronger and stronger until the burnt toast smell turns into an acrid stench that makes his nose sting. A wisp of black smoke floats up the stairwell, alarming Tadashi. "The café's on fire!"

"_What?!_" Cass runs out of the kitchen and joins him at the top of the stairs. "Oh my God!"

"We have to get out of here!"

"Okay, okay—Mochi! Mochi, where are you?" Cass hurries to her bedroom and comes back with the petrified feline.

"Come on!" Tadashi grabs her hand and together they run down the stairs.

The kitchen is engulfed in smoke, making it difficult to maneuver through the café. Tadashi bumps into a table, and he hears Cass grunt as she accidentally runs into the counter. "Tadashi!"

"I'm right here!"

Covering his nose, gropes around until he feels her arm and pulls her away from the kitchen. They finally make it to the outside, where a sizeable crowd has formed in front of the café. Two helpful pedestrians gently lead them to the other side of the street, and someone hands him a bottle of water. He sits on the curb as he takes in two giants gulps before passing it to Cass.

"You… okay?" he gasps out. Cass nods curtly but doesn't stop drinking.

"Someone called an ambulance," the blonde young woman who handed him the water bottle informs them. "You two aren't hurt, are you?"

"No, I'm fine. Aunt Cass?"

The older woman finally sets the bottle down. "I-I'm okay."

He examines her—frazzled hair, soot-stained cheeks, trembling hands petting Mochi almost aggressively—and he nearly gawks at a line of red running down her arm. "You're bleeding."

Cass barely glances at it. "It's just a scratch. I'm fine." He knows she's lying, but he doesn't press her. An ambulance will be here any moment to take care of her.

This was no accident. Aunt Cass keeps the café up to up code and takes the safety of her family and employees seriously; she isn't so careless as to allow her a business she's built from the ground up over so many years to catch fire. But who would want to destroy the café? His eyes sweep the crowd when he suddenly spots something fly over the building.

Sunfire.

From their last encounter, Tadashi isn't surprised in the least that he's the culprit, but knowing this only serves to make him mad. It's one thing to chase him like a fiery wraith; targeting his family, including those of any other reality, is unforgivable.

He needs to end this. Now.

The blare of an ambulance echoes in the distance, followed by the deafening siren of a fire truck. Tadashi stands from the curb. He feels more confident about his next actions knowing that Cass will be in good hands. "Aunt Cass, I have to go."

"What? Wait a minute, where are you going?" Cass tries to stand as well, but Tadashi sets his hands on her shoulders firmly. "Tadashi?"

"I love you, Aunt Cass. Tell Hiro… I'm sorry."

He runs off, ignoring the desperate cries of his aunt. But she's not his aunt, nor is Hiro his brother. They're in another world, waiting for him to return.

But leaving Cass doesn't hurt any less.

He stops in an alley a few blocks away. He's already out of breath, thanks to the smoke that had filled his lungs. His skin is clammy and he's sweating bullets, but he stands assertively in place in spite of these ailments. "Hey! Your beef is with me, not my family!" His eyes sting with furious tears, his throat sore and tight from verbal ire. "If you want me, you got me! Just keep them out of it!"

Two seconds pass, then three, then four…

Then a figure appears, a candescent flame in the darkness of the shady alley. Sunfire lands a few feet in front of him, just within reach. The half-mask on the pyro's face and his thin line of a mouth make him difficult to read. When he speaks, and his voice is just as potent as the scorching atmosphere around him.

"No more running. No more hiding." He holds out his hand, the flames receding.

Tadashi hesitates, his hands trembling. Once he takes his hand, that's it. He can't run or hide from this. He may or may not be able to get home, but at least Hiro and Cass will be safe.

He offers his hand. His fingers nearly graze Sunfire's when a yellow streak breaks their virtual concord. Startled, Tadashi backpedals, trips over his own feet, and falls to the ground. The arsonist's hand recoils, and he looks around for the offender vigilantly.

"Hold it right there, villain!" a nasally voice that sounds an awful lot like Fred cries heroically.

The figure that appears isn't his wily friend, but it does look like something out of his comic books. It's some sort of… monster, with three gold eyes and four serrated teeth in a perpetually open mouth. Fake flames frame its arm, the tangerine color complementing its cerulean body. "Finally! An adversary I can contend with! Hath at thee, fiery fiend!"

As he watches the monstrous being fight the flaming foe, spots begin to dance in his vision. His head feels funny, and it's getting harder to breathe with each passing second.

"Tadashi! Tadashi, can you hear me?"

Before his face hits the pavement, Tadashi sees something big and red land in front of him. A distant voice that sounds suspiciously like Hiro calls out to him.

"_Stay with me, Tadashi! Tadashi wake up! Tadashi! TADASHI…!_"


	9. Chapter 8: A not-so complicated story

**A/N: So I went back and reread some of the chapters and saw a few errors. Turns out no matter how many times I edit a story, I still manage to miss the most obvious mistakes. But that's okay; there's always room for improvement!**

**Now, enjoy!**

* * *

**Big Hero 6: ****The Crossover**

**Chapter 8: It's a not-so complicated story**

"Hey, Aya? Mind taking out the trash? The bin in the breakroom's getting funky."

The young nurse rolls her eyes. "Sure thing, John." Aya wants to remind the boss's son that taking out the trash is below her paygrade, but she'll take any excuse to leave the clinic outside of her 10-minute lunch break.

Going through the back door, Aya puts the bag in the dumpster behind the adjacent building. After dropping it off, she sits in the alley for a moment to decompress. Today's not a heavy work day, but she needs to recharge before she has to go back inside to deal with John and his sycophantic crew. The alley is thankfully empty today; the high schoolers that play hooky either recently had a change of heart and began caring about their education again, or they chose a different venue to sell their bootleg DVDs (who even uses DVDs anymore?). Ten minutes into her mobile game, she decides to go back inside. John has probably realized by now that she's taken advantage of the task he's given her, and the last thing she wants is another lecture from comes-into-work-three-hours-late John.

After finishing level 63 of Pastry Punch, Aya gets up and stretches. As she heads back inside, something thumps heavily behind her. She turns and loses her breath at the sight of a 10-foot tall robot staring her down. Her fight-or-flight instinct has decided to take the day off because all she can do is stare. For some reason, she doesn't feel scared; in fact, she's not threatened by the armored stranger at all. She recognizes it from somewhere… but at the moment, she's drawing a blank.

A smaller violet robot manifests from behind the red behemoth. As it walks over to her, she sees that its legs are very much human. The contrasting sizes of both figures makes the scene more comical than fearsome. She knows them, but from where? From TV, maybe? They do look like something from some superhero flick—

Superheroes! They're the superheroes she's been hearing about lately! What's their name again? Big Hero… Seven? No, six! There's six of them! But where are the other four, and what are these two doing here—in this alley—with her—in the first place? "Can I… help you?"

The smaller violet hero walks up to her at a frenzied pace. The visor on its helmet pops up, revealing the stranger's identity. "Hiro!?" She can't believe it. She had just talked to him an hour ago about Tadashi. She can only imagine what happened between then and now, and why he showed up here, to her place of work, jacked to the nines in superhero cosplay.

"Please help us!"

She looks to the red one (who she's fairly certain is a robot) and finally takes note of the figure in its arms. "Oh my God!" Tadashi's head hangs limp against the bulky arm of the scarlet hero. His skin looks pale and clammy, and his chest heaves up and down in an erratic rhythm. The sight of him sets Aya into what her colleagues likes to call "nurse mode".

"Bring him inside." The big robot moves towards the door and stops. He's twice as big as the door; there's no way he's getting in the clinic. "Oh, right… Hiro, help me with him."

Together, Aya and Hiro haul the unconscious young man into the clinic. She steers them into the closest exam room, which is conveniently empty. Unfortunately, the hallway isn't so bare, and a blonde man in a white lab coat barges into the room a second later looking quite indignant. "Aya, what do you think you're—"

"John, unless you want your colonoscopy twenty-five years early, I suggest you leave and don't breathe a word of this to anyone." John opens his mouth to retort but quickly thinks better of it and leaves.

Once he's gone, Aya gets to work. "Misty eyes...rapid breathing… his nose is filled with soot. Was he in a fire or something?"

"There was a fire at the café."

"He must've breathed in too much smoke. What about your aunt?"

"She should be on her way to a hospital. There was an ambulance in front of the café when we got there."

Aya leans down and listens to Tadashi's breathing. It's heavy and ragged. "And why isn't Tadashi with her?"

"… I didn't want us to be followed."

Before she can try forcing more answers out of him, Tadashi's chest seizes. "Shit!" In the next instant, Aya becomes a blur as she runs around the room, grabbing everything she needs in order to properly treat Tadashi. She sets everything aside, except for a laryngoscope. After propping the metal probe into Tadashi's mouth, she peeks inside and curses once more. "I was afraid of this."

"What is it?" Hiro asks, immediately panicked.

"His throat's swollen up. He can't get enough oxygen on his own." She pulls over the next piece of equipment: a portable compressor system. If this doesn't work, then she'll have to get a doctor in here to intubate him, and that's the last thing she wants to do (aside from explaining why she let a superhero into the back of the clinic without permission). She puts the mask on Tadashi's face and she turns on the machine. A few tense seconds pass with only the sound of Tadashi gasping for air filling the room. When his chest finally moves and his breathing evens out, she sighs in relief. "Thank God."

Hiro is still on edge. "Will he be okay?"

"He's stable, for now. This should bring down the swelling in his throat. But he _should_ be in a hospital. Tell me again why Tadashi isn't in a hospital, Hiro."

"… It's a long story."

"Does this story explain why you look like you're about to go trick-or-treating?"

Hiro rubs his neck sheepishly. "That story is actually shorter. You see, three months ago, I lost my brother in a fire, and I wanted to find the one responsible. It turned out to be one of his professors. I was so mad I wanted nothing more than to…" His fists clench so tight in his lap Aya's afraid he'll hurt himself. After a few seconds, his hands go lax. "Anyway, my friends made me realize that getting revenge wasn't going to get him back, and that's not something Tadashi would have wanted. So instead we stopped Yokai—er, Callaghan, before he destroyed the city."

Aya remembers seeing something about an SFIT professor building an artificial wormhole in front of the brand new Krei Tech building on the news a few months ago. That was when the heroes first showed up.

"So you and your friends and that… thing waiting outside—"

"Baymax."

"Right, Baymax. You're all legit superheroes." Hiro nods. "And what is Baymax exactly?"

"He's a personal healthcare companion. Tadashi invented him, actually. I just added the gear and the butt-kicking program."

"So he's basically a robotic nurse that fights crime."

"Basically."

She takes a moment to review all the information he's given her so far. "You realize how crazy this whole thing sounds, right?" Hiro merely shrugs. "But one thing still doesn't add up. If Tadashi died in that fire, how come he's… _here?_"

"I have no idea. But he's back, and I think it has something to do with that pyromaniac we faced today."

"That's the long story, right?"

"Yeah. It's a bit… complicated."

"More complicated than forming a superhero team to avenge your not-so-dead brother?"

"… Fair enough." Hiro sits in the chair on the other side of the room. "My team and I are currently investigating a theft. I can't say much about it but… what they took, it's extremely dangerous in the wrong hands. So far, we haven't found any clues about the thief's identity. We were having another meeting about it, and I… had to sit it out."

"Your team kicked you out?"

"No." Aya fixes him with a look until he caves. "Finals are next week, and I haven't necessarily been on top of studying—but that's irrelevant! Anyway, that's when I called you..."

**O—O**

"_Hello?_"

"Um… is this Aya?"

"… _Who wants to know?_"

Hiro's caught off guard by her cagey response. "This is Hiro, Tadashi's little brother."

"_Oh, hey! Sorry if I sound a little cranky. I just started my break. What's up? Is something wrong with Tadashi?_"

"No, he's fine. I just had a few questions. You said he was suffering from amnesia. When exactly did his memories start coming back?"

He hears soft humming on the end other. "_Hmm… it seemed like he recovered his memories as soon as he woke up in the café. Why? Is he still having trouble with remembering?_"

"Kinda. I don't know if it's the concussion or what, but he was saying some weird stuff last night. What happened when you found him? What was he like?" He hears something break in the background. "You okay, Aya?"

"_Yeah, yeah! I'm okay. Sorry about that. The clinic's gotten busier all of a sudden. What was your question?_"

"I asked you what happened when you found Tadashi."

"_R-Right. Well, when I found him, he was scared and confused. He couldn't remember who he was or where he came from. But that's completely normal. He has amnesia, and that coupled with the concussion—you can't expect him to recover all his memories overnight._"

"I know, but… can you tell me where you found him?" A longer, unnerving pause proceeds this question. "… Aya? You still there?"

"… _Listen, Hiro, I can't talk about this anymore. This is something you should discuss with Tadashi._"

"But you're the one who—"

"_I have to go back to work._"

"Aya, wait!" The nurse hangs up before he can get more answers.

"Hiro, come quick!" Honey suddenly cries. "Something's happened at the café!"

The young man immediately runs into Fred's room, where the team is surrounding his television. "What's going on? What's happening?" He sets his eyes on the screen and his heart nearly stops. The TV is currently on the news network, and the sky cam that's recording the live events circles around what looks like the Lucky Cat Café. And it's burning to the ground.

Suddenly, Hiro's back at the showcase, watching his brother run into the fire, showers of glass and roaring flames permeating his vision. Only it's not just Tadashi. It's Cass, and Mochi, and all their family memories, burning to a crisp.

Not again. He won't let it happen again. "What are we waiting for? Let's go!"

The team immediately suits up and flies over to the Lucky Cat Café. When they arrive at the scene, Hiro sees the firefighters trying to put out the fire. It seems like they've been struggling for a while. The flames have already reached the top floor, and the hose has done little to douse the inferno. The windows of the apartment above explode, glass raining all over the sidewalk. As soon as they land, Hiro drills out his orders:

"Wasabi, crowd control!"

"Got it!" The green hero immediately plants himself between burning building and the crowd. "Everyone, stay back!"

"Honey, can you douse the flames?"

"Leave it to me!" The pink hero pulls two balls out of her specialized chemistry purse, throwing them into the fire. Once the heat hits the combination of chemicals, a fire-retardant foam explodes inside the café.

"My nephew!" Cass pushes her way to the front of the crowd. Hiro is relieved to see his aunt is safe, but the sight of her bloody arm feels like a shot of liquid nitrogen in his veins. "My nephew was with me! He ran that way!"

An EMT pulls her back. "Ma'am, we need to treat your injuries immediately."

"_Please help him!_"

GoGo, always levelheaded, reassures Aunt Cass, "We'll find him, ma'am." To Hiro, she whispers, "Hiro, snap out of it! They'll take care of her."

"R-Right! Baymax, scan the area."

The robot's eyes trace every outline of the neighborhood until they find their target. "There are two presences ten yards east."

"Take us there!" Hiro, GoGo, and Fred jump back onto the red guardian, and together they make their way to Tadashi's location.

Just as Baymax said, Tadashi is only a few blocks away, and he's not alone. The other figure doesn't look human, though. In fact, it looks like something out of mythology. The blazing being floats toward Tadashi until they're within arm's length and reaches out. To Hiro's surprise, Tadashi reaches out to it as well. "GoGo!"

"On it!" The magnetism expert throws one of her discs at them, separating Tadashi from the masked stranger. Fred hollers in exhilaration and leapfrogs toward them before Baymax can find a safe place to touch down. The overenthusiastic hero makes sure his back is to Tadashi so his exposed flesh is shielded from their scorching battle. Having fallen from the unanticipated disc, the young man merely sits on the ground, paralyzed.

Hiro detaches himself from Baymax as soon as they land. He approaches Tadashi cautiously. He's not sure what that… _thing_ did to him, but the young superhero doesn't have a good feeling. "Tadashi! Tadashi, can you hear me?" The young man doesn't respond. Instead, he falls over, his face hitting the pavement. "No, no, no!" Hiro runs to his older brother, turning him onto his back. The younger boy wants to help him, but he doesn't know what to do. He's not a doctor, and Baymax can only do so much. He does the first thing that comes to mind and shakes him. He can't lose his brother again—he just can't! "Stay with me, Tadashi! Tadashi wake up! Tadashi! TADASHI!"

"Hiro! Calm down!" GoGo is next to him in an instant, holding him back. "Baymax, what's wrong with him?"

The healthcare companion quickly scans the unconscious young man. "Tadashi is currently suffering from smoke inhalation. He needs immediate medical attention. Suggested location: San Fransokyo General Hospital."

"Hiro, take Baymax and get Tadashi to the hospital. I'll help Fred." GoGo skates away, leaving the distraught boy with his comatose brother and his controversial thoughts.

"I don't get it," Hiro mumbles to himself. "Why did Tadashi come out here alone? Who is that guy and how does he know my brother? What does it all mean?" He can't make neither heads nor tails of any of it…

But he knows someone who might.

"Baymax, we're not going to the hospital."

"But Tadashi—"

"If we take him there, that guy might follow us." Hiro opens a hidden component in his left glove and enters the coordinates to a safer location. "Baymax, I'm sending you new coordinates." He then tries to heft Tadashi into Baymax's arms as gently as he can (though Baymax does most of the work). Once Tadashi is safely in the healthcare robot's grasp, the teen climbs back onto his partner's back. "Let's fly, Baymax."

**O—O**

"So you're telling me the reason you didn't want take Tadashi to the hospital is because you believe this… _fire-man_ is targeting him?"

"In a nutshell."

Based on their prior conversation, Aya has a sneaking suspicion she knows who the villain in the story is. "W-What did this guy look like again?"

"He was dressed in black and covered in flames. And he had a mask." She bites her lip nervously. "You know who it is, don't you?" Instead of answering, Aya crosses her arms and turns away, careful to avoid knocking over the machine supplying Tadashi with oxygen. Suddenly Aya is trapped between the occupied table and the vertically-challenged teen. "During our call, you hesitated when I asked about where you found Tadashi. It has to do with our villain, doesn't it?"

"… Even if it does, it has nothing to do with me. I don't want to get into any more trouble than I already am. I'm risking my job just letting you in here. And what are you going to do about Tadashi? He can't stay here." Hiro just looks at her expectantly. "No! Absolutely not!"

"I already have a place to take him. I just need help bringing him there."

"Can't you call your superhero buddies to give you lift?"

"They're probably still going after the fire guy. Besides, it would look super suspicious if anyone saw a bunch of superheroes carrying an injured civilian _away_ from the hospital."

"Oh, and it doesn't look suspicious when two of those superheroes smuggle a civilian into a free clinic _through the back door_!"

"Look, I know I'm asking a lot, but if we take Tadashi to the hospital, that guy will most likely find him there, and innocent people might get hurt."

Aya ponders her options. She could just walk out of this room and let Hiro and his friends deal with this issue on their own. She'd be safe and she wouldn't have to hear about Sunfire ever again…

But if what Hiro said is true, the casualties caught in the crossfire of the inevitable battle between Sunfire and Big Hero 6 would be reduced to none if she helps him. The only thing she has to lose in this situation is her job, and there would be no love lost between her and her coworkers if John does rat her out. Plus, as much as she hates to admit it, she knows that helping them is the right thing to do (cue after school special music).

"Damn it…. I'll be right back." She leaves Hiro to try and find something to transport Tadashi from the exam room and to her car. She retrieves the folded gurney they keep in the storage closet in case someone needs to be transferred to San Fransokyo General. She returns with it unfolded and helps Hiro carefully lift Tadashi and the compressor system onto it. "Take him outside. I'll pull my car up to the back."

When she drives up near the back entrance, she sees that Hiro is alone with his unconscious brother. When she asks about Baymax, Hiro explains that he sent him away to notify the others. Together, they transfer the comatose patient as carefully as possible into her backseat. Hiro settles himself on the floor beside Tadashi so he can monitor his condition.

Once she's at the wheel again, Aya hands him her phone. "Enter the address so I know where we're going."

He does so swiftly and hands the phone back. The address she sees nearly makes her eyes bulge out of their sockets.

"You've got to be kidding me."

**O—O**

For the fourth time in 24 hours, Tadashi wakes up in a very unfamiliar place, and it's the worst awakening so far. The moment his eyes open everything is a fuzzy blur of colors and shapes that make his head feel like a shaken snow globe. Every breath is sharp and excruciating, like shards of glass are cutting the inside of his throat. His body feels like lead, and the effort it takes to lift his head is painfully slow and pathetic. It's a frustrating experience. For once, why can't he just wake up like a normal college kid who wastes nights playing videogames instead of cramming for exams instead of an unlucky college kid who's being chased by a supervillain who can fly and project fire?

Blinking the fuzziness out of his vision, the first thing Tadashi can just barely make out are the spines of books that look to be about fifty years older than him. A bookshelf. Next to that a desk. And right next to that, a window. It's dark outside. How long has he been out?

A creak from the corner of the room indicates the opening of a door, and the soft click the closing. Tadashi waits with bated breath as the person walks over to him. When they lean over, he's relieved to see it's not Sunfire.

"Look who's finally awake."

"A-Aya…" His voice, which is so hoarse it sounds as if he just smoked a whole pack of cigarettes, is foggy and hollow. He hacks up a harsh cough, and the feeling makes the metaphorical shards of glass in his throat cut deeper into his larynx.

Aya reaches forward and removes what looks to be an oxygen mask from his face before lifting a glass of water to his lips. He drinks greedily and coughs most of it back up. Aya helps him sit up so he can catch his breath. "Aren't you supposed to be a super smart robotics nerd? How many times do I have to warn about drinking too fast?"

"S-Sorry."

"Don't talk, just drink. _Slowly_." This time Tadashi takes his time and savors the cool sensation alleviating his aching throat. After a few minutes, he sits back against the plush pillows supporting his upper and lower lumbar regions. Aya puts the mask back on his face and fiddles with a device next to his massive bed. A quiet hiss slides through the tube and soothing, life-giving air enters his nostrils and lungs. "Better?"

He nods. "Where…?"

"We took you to your friend's fancy mansion. I gotta say, I knew your friends were interesting characters, but this is … insane! I could fit my whole apartment building into Fred's place." What is she talking about? He's never even seen the inside of Fred's house before (and Tadashi would be lying if he didn't half-believe the rumors about the school mascot living in the basement of the research lab), but he'd know if he was living in a mansion. "Not to mention you're friends with a bunch of superheroes."

… What was that?

"You haven't secretly been a vigilante this whole time, too, have you?" Her playful tone makes Tadashi believe she's joking, but the look on her face belies her flippant question. What exactly happened while he was unconscious?

"What are you… talking about?"

Aya observes the robotics student critically. "Tadashi, what's the last thing you remember?"

He tries to recall, pushing past the ache that comes with thinking. The fire at the café. Sunfire. He ran away because Sunfire caused the fire and hurt his aunt—

"Aunt Cass!" Tadashi tries getting out of bed, but the insufficient amount of air in his lungs and his appointed nurse stop him before he can do much else. "W-Where… where is she? Is she… okay?"

"Calm down! I called the hospital and they said she's fine. She just needed a couple stitches and treatment for inhaling all that smoke, but she'll recover. You should have joined her, but your brother somehow convinced me that bringing you here would be safer for everyone."

"Hiro…?" Oh, yeah. He would have been at school during the fire. But what Aya said a few moments prior suddenly has him thinking again. "What were you… saying earlier… about my friends being… superheroes?"

Aya's face goes through a transformation of different emotions until it finally settles on one that is very familiar to Tadashi: annoyance. "Of course they'd hide something like this from you. You've been supposedly dead for three months."

"I… what?!"


	10. Chapter 9: You'll never believe this

**Big Hero 6: ****The Crossover**

**Chapter 9: You'll never believe this**

The ride to Fred's house feels like a millennium to Hiro. He dreads each second, waiting with bated breath for Tadashi's condition to worsen as Aya yields to stop signs and red lights. As he grips his brother's hand, the young hero subconsciously rubs his thumb down his wrist, reassured by the steady pulse as well the rise and fall of Tadashi's chest and the fog forming and waning inside his oxygen mask.

As if sensing his unease, Aya grips his shoulder and gives it a soft squeeze. "Everything will be okay, Hiro."

"… I lost him once before to a fire."

The nurse turns back to the wheel to focus on the road. "I know. But his condition's not life-threatening. You don't have to worry. I won't anything happen to him under my watch." She smiles at him through the rearview mirror, and his grip on Tadashi's hand slackens slightly.

Finally, the millennium ends and they arrive at Fred's place. As soon as the car is parked, Hiro runs to the entrance and tells Heathcliff to get Baymax. The butler comes back with the giant marshmallow a few minutes later, followed by the rest of BH6.

"Hiro, what's going on?" asks Honey Lemon.

Before he can answer, Aya exits her car and walks to the other side so they can unload their smuggled patient. When they see who it is, the rest of BH6 gawks.

"What the hell is he doing here?" demands GoGo. "You were supposed to take him to the hospital!"

Hiro ignores his friends as he helps Aya lift Tadashi into Baymax's arms. "So that's what he looks like," Aya muses as she walks next to the healthcare robot. She carries the compressor with care as she monitors Tadashi, making sure not to accidentally pull off the oxygen mask. Heathcliff leads them to the closest guestroom where they setup Tadashi and the compressor. Hiro reaches to close the door, but a foot steps into the threshold before he can.

"Explain, Hamada." GoGo glares down at him with the malice of a viper, but Hiro is too concerned about his brother to care about his own safety.

"I'll explain later. I promise." He shuts the door and locks in an afterthought. After slamming the door in her face, he doesn't trust the speed demon or the others not to barge in.

Joining Aya and Baymax at the bed, Hiro watches them work as he observes his brother. His breathing hasn't changed, but the pallor in his skin has gained some color. While Aya makes some adjustments to the compressor, Baymax does a diagnostic scan on the unconscious young man. "My sensors are detecting a long-acting beta-agonist and corticosteroid solution in Tadashi's respiratory system."

"What does that mean?"

"It means Tadashi is starting to breathe on his own again," Aya clarifies. "Right now, the compressor is circulating an anti-inflammatory drug along with the oxygen into Tadashi's lungs. We usually only use it on people who suffer from asthma attacks."

"Is that what happened to Tadashi at the clinic?"

"Basically. Since he doesn't actually have asthma… does he?" Hiro shakes his head. "Since he doesn't have asthma, he should recover within a few days."

"Based on the dosage of the long-acting beta-agonist/corticosteroid solution, Tadashi's respiratory system should recover in approximately twenty-four hours with proper bedrest."

Aya looks at Baymax, unamused. "Thanks for clarifying."

"I sense you are being… sarcastic."

"That is correct."

Hiro snickers at their banter. Aya may seem annoyed, but he knows she's fascinated with Baymax. "Thanks, Aya. I owe you big."

"No, you don't. Your aunt already gave me free coffee for life. Your debt's been paid a hundred times over." She checks her phone before heading towards the door. "Mind pointing me to the closest bathroom?"

"It's just to the right. But I have to warn you my friends will probably pounce on you for answers as soon as you leave the room."

She gives him a wry look. "Six days a week I deal with loud families, hypochondriacs, and people who shouldn't be licensed to practice medicine; I think I can manage." The nurse unlocks the door, slides through the jamb, and closes it in a blink of an eye. Shortly after, Hiro hears his friends questioning her, and the voices fade further into the hallway.

He's never felt more indebted to a stranger. He has no idea what he'd do without Aya. Tadashi may have built Baymax to be deal with medical emergencies, but he obviously forgot to include a few things. Baymax wasn't equipped to help Tadashi back in the alley. He'll have to fix that later.

Right now, Hiro confronts the millions of questions that have multiplied since he'd found Tadashi with that stranger.

First question: what the hell was that knucklehead thinking!? They've only been reunited for less than a day, and Tadashi had nearly died—again! And minutes after escaping the inferno, he's with the arsonist. At first, Hiro thought the fire freak had confronted his brother, but it turns out Tadashi was the one doing the confronting. Now that he's thinking more clearly, he doesn't remember seeing any signs of a struggle; Tadashi must have led him there all on his own. You'd think someone who has survived more than one fire would have a reinforced sense of self-preservation, but not Tadashi. No, he always has to be the "hero".

Second question: why? Why would Tadashi lead the arsonist away? Unless he was right and Tadashi really was his target from the start. But why was this guy after his brother? What had he done to gain this maniac's attention? It must have something to do with the fire from three months ago.

Which leads to the ultimate question, a question that's been haunting him since the night of Tadashi's return:

What happened to his big brother?

A groan comes from the occupant beside him, and Hiro watches as Tadashi shifts in his sleep. He doesn't wake up, much to Hiro's relief. Tadashi would definitely not be okay with his next actions. "Baymax, scan Tadashi again. Look for anything that shouldn't be there."

Baymax's eyes buzz softly as his scanners analyze Tadashi. A few seconds pass before the buzzing stops, and the healthcare robot reports his analysis. "There is nothing wrong with Tadashi. However, I do detect something strange in his nervous system, particularly in his cerebral cortex."

Hiro blanches. "W-What is it?"

"I do not know. The substance is not in my database. But it is not affecting Tadashi's nervous system in any way. It is completely harmless." That comforts the teen a little, but barely.

Hiro runs a hand through his scruffy hair in exasperation. He'd hoped his hunch was wrong, that there was nothing different about Tadashi, that this was the same brother he'd known since he was born. Now that Baymax has confirmed it, he can't deny it any longer. It's moments like this that make him deplore his own genius.

Before Hiro can ask more, Aya slides her way back into the room with a glass of water. "Next time you tell someone where the bathroom is, be more specific! There are, like, a million rooms 'to the right'!"

Hiro puts his jittery hands in his pockets. He stumbles to reply, still flabbergasted by Baymax's discovery. "S-Sorry. Wasn't thinking…"

Aya doesn't seem to notice his agitation as she heads over to the other side of the room to take a seat at the desk. "Thankfully, the butler told me where it is. Your friends were no help, either. Every time I asked them a question, they just answered with another question. Guess who they were asking about." Hiro rubs the back of his neck guiltily. "You should really go out there and explain what's going on, Hiro. They're just as worried about Tadashi as you are."

He shifts away from her, and Baymax, and Tadashi. Even with his back turned to them, he knows Baymax can still sense his uncertainty. Thankfully the robot has the tact to not say anything to the other conscious occupant of the room. He knows he needs to tell his friends about Tadashi, but he still has so many questions. He'd rather wait for his brother to wake up and get some answers than explain his paranoia to his friends.

Sighing in defeat, Hiro heads toward the door. He hesitates as soon as his hand grasps the knob. "You'll watch him, right?"

He can practically feel Aya roll her eyes. "Of course I will. It's kinda my job."

"Thanks… Will you tell me when he—"

"Go already!"

"R-Right!" Hiro hurries out the door before the nurse can physically throw him out. As he meets GoGo's ice-cold stare, he can't decide which of the two young women is scarier.

**O—O**

"Hiro, this doesn't make sense."

"Yeah, why would that guy be after Tadashi?"

"I don't know, but…" Hiro looks around at the faces of his friends, who are all giving him similar looks of puzzlement. He expected this reaction.

After calmly informing the rest of BH6 of Tadashi's condition, he explained the reason behind his rash decision of bringing the comatose man here instead of taking him to the hospital. Needless to say, the older members aren't convinced (except for Fred, who looks distracted for some reason). But being the obstinate teenager he is, their doubt makes him want to prove his theory even more.

"Look, just—just hear me out!" Everyone quiets down, taken aback. They haven't seen Hiro this worked up since he almost made Baymax end Callaghan's life. "I know it sounds crazy, but why else would Tadashi have gone to that alley?"

"How do you know Tadashi was there of his own volition?" Honey Lemon asks. "The arsonist—"

"Fire Starter!" Everybody stares at Fred. Seeing the attention suddenly on him, the superhero fanatic apologizes, "Sorry, don't mind me. Just thinking of a villain name."

"… Like I was saying, the arsonist could have taken Tadashi."

"Cass said he ran off," GoGo remembers. "But that doesn't mean you're right."

"Anyone else think it's weird that the fire and the theft at Krei Tech happened within a few days of each other?" asks Wasabi.

Noting the spontaneous glint of excitement in Fred's eyes, Honey Lemon struggles to quell the brewing storm of exposition that's about to come. "That's just a coincidence! Crimes happen all the time!"

"But what if—"

"But what if it's the same villain," Fred interjects, standing and pointing to the ceiling for emphasis, "who's committing these crimes?"

Honey Lemon massages her temple. "Oh, boy…"

Wasabi crosses his arms and pouts, irked at having his thunder stolen. "Yes, Fred. Thanks for that."

"So what _you're_ saying," GoGo says, looking pointedly at Fred and Wasabi, "is that the person who stole the portal from Krei is the same person who not only set the café on fire also the same guy who _you_—" she switches her gaze to Hiro "—think is trying to kidnap Tadashi."

The male members of BH6 exchange glances before replying with a concurrent, "Yeah."

"Okay, then. So assuming you're right—"

"And that's a really big if," Honey Lemon hastily adds.

"—that still doesn't answer our earlier questions. Who is this guy, and what does Tadashi have to do with any of this?"

"I think I can… shed some light… on this." Everyone jumps up when they hear the breathless intruder. Tadashi leans against the door of Fred's room, supported by his alleged night nurse, who looks uncomfortable for having to intrude on their "superhero meeting".

"What do you think you're doing, man?" Wasabi cries, outraged.

"You need to go back to bed!" says Honey Lemon. "You can barely stand!"

Tadashi ignores them and continues further into the room. Seeing him struggle to breathe, Wasabi goes over to help Aya quickly usher their friend into the closest seat. GoGo pointedly glares at the night nurse, who merely shrugs and mouths something that Hiro can barely make out.

Once he's seated, Tadashi takes a moment to examine the room. "Why doesn't it surprise me that Fred has a secret double life as a millionaire and a superhero?"

"Actually, my parents are millionaires. But I get that a lot."

Hiro walks over to his older brother, rubbing his arm insecurely. "You… don't seem so surprised by any of this. Does that mean you know...?"

"Aya pretty much told me you all are superheroes as soon as I woke up."

Everyone looks to the nurse again, who again just shrugs. "He was going to find out sooner or later."

"But this is nothing compared to what I've been through these last few days. Or I guess I should say these last three months." Tadashi chuckles darkly under his breath. Hiro balks at him, unfamiliar with this cynical side of his brother.

"So you do know this arsonist guy?" Wasabi asks.

The older Hamada nods somberly. "His name's Sunfire."

"Cool villain name," Fred quips, earning an elbow jab from GoGo."

"He's the first person I encountered when I… fell into this world."

A pause fills the room with palpable feelings of shock, disbelief, and a teensy bit of anger. No one knows how to react. Not even Fred can come up with some otherworldly explanation to Tadashi's weird statement.

"Now neither of you are making sense," says GoGo irately. She looks ready to punch anyone and anything within range, including the young man who's still struggling to breathe. "What do you mean you 'fell into this world'?"

"Just what I said. I fell into this world."

"This is crazy, Tadashi," says Wasabi.

"Yeah, this isn't funny," says Honey Lemon, though Hiro can tell just by looking at his previously deceased brother that he believes every word that he's saying. He knows Tadashi would never joke under such humorless circumstances. Then again, according to Tadashi himself, he may not even belong in this world at all, which would also explain his weird behavior from the day before.

Because of this, Hiro's not ready to dismiss this bit of enlightening news as quickly as the others. "Why do you think that?"

Tadashi sits silently for a moment, and Hiro can see the metaphorical cogs spinning behind his analytic gaze. "I need you guys to explain something to me first. What happened to me when I disappeared?"

"You didn't disappear."

"Hiro, maybe you shouldn't…"

"If he doesn't know already then maybe what he's saying isn't nonsense!" He doesn't mean to snap at Honey, but he has to know. He has to know why the Tadashi he's looking at feels like a complete stranger to him, and why his being from a different world is making more sense than anything that's happened since his homecoming.

And so Hiro tells him about the showcase and the fire that supposedly ended Tadashi's life. He tells him about finding Yokai, who was later revealed as Callaghan, and his plot to avenge his daughter by destroying Krei's livelihood and the billionaire himself. He tells him about the formation of Big Hero 6 and stopping Callaghan, smoothly glossing over the part about trying and failing to make Baymax destroy the former SFIT professor.

And while he's telling him all this, the others lapse into a solemn, reminiscent silence. None of them like remembering that bleak part of their lives. Even Aya, the outsider, looks saddened by the recollection of these events. Tadashi, on the other hand, looks like he's trying to piece together a 1000-piece puzzle in his mind. When Hiro first brings up his fiery death, he initially looks devastated, but as the story continues his face slowly transitions from horrified to confused to a myriad of other emotions Hiro can't even read.

Once he's done recollecting the last three months, Hiro and the others watch Tadashi's reaction with bated breath. "So… basically I should be…" No one wants to answer the silent inquiry, but Hiro nods all the same. Tadashi lets out a breath, wiping a hand over his forehead. "Okay… that explains a lot."

"You shouldn't have survived."

"Hiro!" The others gap at him like he's committed blasphemy, but he ignores their judgmental looks.

"So how did you?"

Tadashi isn't put off by the blunt question. "The day of the showcase, I didn't die in a fire. I fell into the portal Callaghan built to find his daughter."

"But Callaghan didn't know Abigail was still alive."

"Yeah, and he didn't build the portal," says Fred.

"Well _my_ Callaghan did. And Abigail was helping him. Long story short, she got stuck on the other side, and all he wanted to do was get her back. I wasn't so sure if she was still alive myself, but when he asked me to assist him, I wasn't going to deny helping a father reunite with his daughter. We were making the final adjustments to retrieve Abigail when Hi—" Tadashi pauses, catching Hiro's eye, and corrects himself. "W-When someone broke into the lab. By the time I got to them, the portal was destabilizing. I saved him, but then I got hit by a metal beam that came loose due to the vacuum generated by the portal. The next thing I knew, I landed here. I didn't realize I was in the wrong world until after I talked to Hiro."

Silence takes over the room once more as everyone tries to fathom the unbelievable veracity of Tadashi's story. "H-How is this possible?" stammers Honey.

"It's not," GoGo insists. "This is something out of Fred's comic books."

"Like a bunch of college kids being superheroes?" Tadashi quips.

"Tadashi, man, this is a lot to take in," says Wasabi.

Tadashi immediately looks contrite. "Sorry. I know this doesn't make sense, but I've spent the last twenty-four hours trying to understand it, too. It's the only logical explanation for why none of my memories match any of yours, and it's the only reason I can imagine as to why Sunfire is after me in the first place."

"But, dude, if what you're saying is true," says Fred, "that means—"

"You're not our Tadashi." The words, as bitter as they are to say, ring with truth. "You're… not my brother."

Tadashi—the fake one who he almost replaced with his true brother—meets Hiro's disappointed gaze and grimaces. "No, I'm not. I'm so sorry, Hiro."

"… I knew it was too good to be true." Without pause, Hiro runs out of the room. He had a hunch—it was just a stupid _hunch_, but knowing that he was right doesn't make the truth any less excruciating.

**O—O**

As soon as Aya steps outside of the mansion, she takes in a deep, rejuvenating breath. The tension in there was suffocating, even after Hiro left the room. But she can't blame him; she'd be upset, too, if she found out her dead sibling who came back to life turned out to be from some alternate universe…

Scratch that. This whole situation is way out of her depth. First the discovery of BH6's identity, then learning of Fred's affluent background, and now, the icing on the cake, Tadashi's other-dimensional origins! It's like she's living every comic book nerd's dream!

Aya heads to her car, intent on running some errands before returning to the mansion. Hopefully things will settle down while she's gone.

Fred let her stay the night, but there are still a few things that she wants to get done before it gets too late. She doesn't know how long she plans on hiding out with the superheroes, and she wants to get as much done as possible before hunkering down for who knows how long to take care of Tadashi. And after spending a few minutes with Baymax and learning the extent of his medical programing, she figures the danger-prone moron can survive a few hours without her.

Tadashi didn't pull out any stops when creating the giant marshmallow. She wouldn't be surprised if Baymax knows just as much as, maybe even more, medical procedures than she does. And with such a soft, huggable appearance he's basically the perfect healthcare companion. She would have been miffed at the fact that his very existence made her job obsolete if she wasn't so impressed by Tadashi's ingenuity, not to mention his ambition to help others even at the risk of his own safety.

Tadashi's caring capacity amazes her. The look on his face after Hiro left breaks her heart just thinking about it. He may not be his real brother, but everyone in the room could plainly see that Tadashi definitely cares about this Hiro just as much as his own. He couldn't lie to him, but he didn't want to hurt him, either. And as much as she wanted to follow Hiro, she and everybody else agreed to leave him alone for now. Tadashi looked ready to bolt after him, but his friends pretty much trapped in the chair to prevent such a predictable move. Even though she's only known them for less than two days, Aya knows that both of the Hamada brothers, no matter which dimension they come from, are equally stubborn. They will make up, eventually. And if they don't by the time she gets back, then she'll make them.

Her first stop is her apartment. Sunfire doesn't know where she lives (thank goodness) and he probably doesn't even remember her face, but she still doesn't feel comfortable leaving BaoBao alone overnight. After packing a few extra clothes, some toiletries, and BaoBao's essentials, she and the Jindo make their way to the hospital.

Aya hasn't talked to Nicki since yesterday. There are only 30 minutes left before visiting hours are up, and she doesn't want to get kicked out of the hospital as soon as she gets in. Thankfully, neither Nick nor the nurse charged with Tadashi's care are in sight, and she and BaoBao make it to the ICU without running into any trouble.

"Hey, Kim," she politely greets the woman at the front desk.

"Hello, Aya." BaoBao goes behind the desk, begging for attention. "And hello to you, too, cutie. You look like you're trying to hide from someone."

"I'm not trying to hide... This is completely unrelated, but Nicki's not around, is she?"

Kim laughs and shakes her head. "She's been busy in the pediatric ward all day. What'd you do this time?"

"Nothing, I swear!" Kim gives her a disbelieving look. "It's a long story."

"I'm sure I'd love to hear it."

"I'm sure you would, too, but I'm saving it for someone else."

"Well, you got an hour, so you better make that story quick." Kim goes back to her paperwork, and Aya smiles gratefully at the older woman.

"Thanks, Kim. You're the best."

"And don't you forget it."

Coaxing the Jindo along, Aya makes her way down the hallway until she reaches the room on the end. Inside is a woman. From the pristine way she's lying in bed, blissfully unaware of her visitors, no one would suspect that she's sick. Or that she may never wake up again.

"Hey, Mom. You doing okay?" There's no response, and the only noises filling the room are the beeps and clicks of the machines keeping her mother alive. Aya sighs, disappointed. No progress so far. That's to be expected, but it still leaves her wanting. A twitch, a wiggle, some sort of sign that her mother will eventually come back to her. But she receives nothing, and the hope in her heart falters.

BaoBao immediately runs up to the bed, but he doesn't jump on. He's been weaned of that particular behavior since their first visit. "Okay, BaoBao. You can go up." Permission given, he gently climbs onto the bed, lying by the woman's feet. They both miss her constantly, so Aya makes sure they visit every day, even when it's late. And as much as she's afraid of Sunfire, she isn't going to allow the threat of his existence stop her from visiting the only family she has left.

"Sorry we're late." Aya settles into the chair next to the bed. "You'll never believe the day I just had…"


	11. Chapter 10: Another long title

**Big Hero 6: ****The Crossover**

**Chapter 10: My brother from another mother-loving dimension**

As Tadashi opens the 14th door down from his own room, he groans in disappointment when he sees it's just another extravagantly-decorated, vacant guestroom. The others are currently asleep and Aya is still doing errands, so there's no one to stop him from finding Hiro.

After the teen ran away, Tadashi was stuck dealing with the reactions of the others. Surprisingly, his friends took the news with stride. They admitted it was still a little hard to believe, but even after he dropped that other-dimensional bombshell on them, that wasn't going to change how they saw him. It comforted Tadashi to know that his friends will always be his friends, no matter what alternate world they happen to come from.

Aya hadn't said a word throughout the whole exchange, simply observing everyone as if she were watching a daytime soap opera. It seemed no one even remembered she was there until she announced that she was going to some quick errands. She didn't bother to pretend she understood any of it, but she didn't look at him any differently, either. She also promised to keep everything secret when the others started to panic. "Who would believe me?"

The only person who didn't accept this new development was Hiro.

Tadashi wanted to go after him, but his friends stopped him and advised him to let his pseudo-younger brother cool down. As Big Hero 6 (he's not sure he'll ever get used to referring his friends as superheroes), they decided to stop their investigation and regroup tomorrow, electing to stay at Fred's for the night. As they all parted ways to pick their rooms, Honey Lemon kindly helped him back to his room before retiring for the night.

"Don't worry about Hiro, Tadashi. It's been a weird night. We all have a lot we need to process. He'll come through. You're still his brother, after all."

Despite Honey's consoling words, Tadashi knew he couldn't sleep until he spoke to the teen himself. So, 45 minutes later, Tadashi finds himself at the 15th empty room. It hasn't been a far walk, but for a man who is still recovering from escaping a fire, it feels like he just ran a 15K marathon. And this is just the first hallway full of guest rooms in Fred's house.

At the 16th room, he rests against the door. "There has to be… an easier way… to go about this…"

"Hello."

Tadashi stifles a shout and clutches his palpitating chest. When he sees it's not a threat, he relaxes and lets out a breath. "Oh, Baymax, it's just you… wait, how'd you sneak up on me?" The robot merely blinks at him and tilts his head adorably. "Never mind. Do you know where Hiro is?"

"Hiro is currently hiding on the balcony. His current hormone levels and increased heartrate indicate that he is very upset."

"I know. It's my fault he's upset. Can you take me to him?"

The healthcare robot's eyes scan the young man. "You are still suffering from respiratory issues due to the inhalation of smoke. Recommended treatment: water and plenty of rest."

Tadashi nearly groans. He might have made Baymax a little too thorough. "I'll rest later, Baymax. Right now, I want to help Hiro. Help me help him. Please."

"… If it will improve your health, I will help you both." The giant marshmallow offers him a white, squishy hand, and Tadashi gladly accepts it.

Slowly, the two make their way to one of the many balconies outside many of the rooms in Fred's inconveniently large house. It's a slow journey; Baymax wasn't built him for speed, and every once and a while Tadashi has to take a break to catch his breath. Ten minutes later, they finally make it to the balcony where Hiro has curled up in a corner. His arms are wrapped around his knees, and his face is hidden. Tadashi approaches him as cautiously as he would a frightened baby deer. Hiro doesn't make any indication that he's aware of his presence, so Tadashi inches closer and closer until he's sitting next to the teen. They sit together in silence, neither addressing the other, and Tadashi is rendered speechless by his own speechlessness. Even after searching for him for half an hour, he still doesn't know what to say.

"Opening up a dialogue usually helps address the problem, and it can lead to a better understanding of one another's feelings."

Tadashi glares at the robot. "Thanks for that, Baymax. I was just about to do that."

"You are welcome."

"I… Hiro, there's nothing I can say to make the situation better. It must be bittersweet to get your brother back only to realize… he's not actually back. I didn't intend to hurt you by being here. But just because I'm not your real brother doesn't mean I care for you any less."

"… I knew you weren't my brother."

That's the last thing he expects to hear. "You did? When'd you figure it out?"

"You were acting weird last night… Plus, when you were unconscious, I had Baymax scan you."

"… Oh."

"I wanted to cover all the bases since we couldn't bring you to a hospital. I'm not sure if I compared them to the ones of…" Hiro hesitates, but Tadashi knows what he wants to say.

"Your Tadashi," he offers.

"If I compared your scan with his, I'm not sure if I could tell the difference between the two of you. But if Baymax hadn't found that thing in your brain, I'd probably just let it go—"

"Wait, wait a minute. What thing? What did Baymax find?"

Hiro looks embarrassed for blurting out this discovery. "I-It's not a bad thing! Baymax says it's not affecting you in any way." Hiro shrinks back into himself. "But that doesn't change the fact that my Tadashi… h-he's is still g-gone."

As soon as he sees the quaking shoulders, Tadashi takes the younger boy into his arms and holds him tight. Hiro grows stiff at first. But then his arms gradually wrap around his back and his hands grasp at his shirt for dear life as he sobs heavily into Tadashi's chest. A few tears escape his own eyes, and Tadashi's hold grows firmer around the teen. "I love you, bro… and I know other me agrees with the sentiment."

A laugh bubbles against his chest followed by a hiccup. Pulling away, Hiro quickly wipes his eyes and nose before meeting his gaze. "This is so weird. I have two brothers now… wait a minute. That's not going to cause some sort of space-time paradox is it?"

"… You know, I'm not completely sure. Technically since the other me is… no longer here, my presence shouldn't affect this world, but there's still so much we don't know about this field of science. Einstein had a theory that—"

Hiro blows a raspberry to interrupt him. "Okay, you're definitely Tadashi. You're just as nerdy as mine, anyway. I feel so bad for the other me."

Tadashi nudges him playfully. "Hey! Other you isn't a picnic, either. And you should talk about being nerdy, Mr. I'm-the leader-of-a-superhero-team. If anyone was going to become the first superhero in San Fransokyo, I figured it'd be Fred."

"Technically, he is one of the first."

"Yeah, but it was _your_ nerdy idea."

"Whatever, nerd."

"Your hormone and neurotransmitter levels indicate that you are both… happy."

The brothers stop their friendly banter and look up at the healthcare robot. Exchanging glances, the boys smile and laugh once more. Things are far from normal, but at least they can cope with that fact that the weirdest thing in the room will always be Baymax. The thought comforts Tadashi, and if this Hiro is anything like his own, then he's sure that he'll move past this mess very soon.

"So… now what?"

Tadashi coughs. "Well, according to my healthcare robot, I need to get rest so I can get better. We should probably go to bed."

A mischievous gleam sparkles in Hiro's eyes. "Or…"

**O—O**

For the first time in nearly three days, Hiro is able to get a few hours of shuteye. After depriving himself of proper rest for fifty-six hours, nothing feels more refreshing, especially after that life-changing heart-to-heart with his alternate world brother who sucks at videogames just as much as his reconfirmed dead brother.

Stretching and yawning, the teen hesitantly rolls out of his snug cocoon of blankets and pillows and sluggishly heads to the door to hunt for some breakfast. Which is a challenge in and of itself considering Hiro doesn't know where the kitchen is. Fred's never given them an official tour, and whenever they meet at the mansion for superhero meetings Heathcliff is always there with snacks prepared for them. He thinks of calling the butler himself when a peculiar sight greets him at his door.

An adorable black and tan Korean Jindo, who has probably been sitting there for a while, patiently looks up at him. "Um… hello, little guy." He's seen this dog before, but his mind is still fuzzy from sleep and he doesn't want to think until he has at least three chocolate chip pancakes in his stomach.

As if reading his mind, the Jindo stands from its spot and walks down the hall. Hiro follows him, questioning his choice to follow a strange dog and hoping that it'll lead to food, when an appetizing smell drifts into his nostrils. When they reach the stairs, Hiro forgoes safety and common sense by sliding down the lacquered banister. The dog runs after him, and once they both reach the bottom, it gives him an indignant look. "What?" The dog moves on, and Hiro swears he heard it scoff at him.

The delicious smells get stronger the closer they get to the kitchen. Hiro races ahead of the annoyed canine once he sees a pair of swinging doors that lead to a masterfully set dining room. The long, rectangular table is filled with all sorts of foods—sandwiches, fruit, sausage, a whole assortment of fancy finger foods that Hiro can't even name—but his sights are set on only one thing: Heathcliff's chocolate chip pancakes with boysenberry syrup. Aunt Cass is the master when it comes to pastries and coffee drinks, but right now her pancakes are second best.

(Somewhere in San Fransokyo General Hospital, a woman is suddenly overcome with the feeling of betrayal and immediately starts plotting her revenge.)

"Look who's finally up!" At the head of the table is an amused young man with an equally disheveled head of bed hair. There's a clean plate in front of him, with the exception of a few crumbs and spots of syrup bordering the edge. "Good afternoon, Sleeping Beauty," he further teases. Hiro ignores him and begins filling an empty plate full of pancakes. "You know, there are other food groups in the pyramid."

"I don't see you grabbing any fruit," rejoins the famished boy genius.

The dog who led him to this beautiful breakfast bounty barks at him for the first time, and this time Hiro actually hear its cross tone. As a gesture of thanks, Hiro throws him a sausage. It catches the link and retreats under Tadashi's chair to munch on his treat. "I see you've met BaoBao again."

"BaoBao?" Hiro echoes with a mouth full of pancake.

"Well, his real name is Bao, but BaoBao's his nickname."

"That doesn't make any sense. His nickname is longer than his real name."

"I dare you to take that up with Aya."

Hiro nearly chokes and winces as the half-chewed pancakes get stuck in his esophagus. He would rather go back into the portal again than deal with Aya's wrath. As a nurse, her commanding disposition and take-charge personality makes her a valuable asset in the medical field, but after facing a fraction of her fury yesterday, the last thing Hiro wants to do is trigger her bad side with something as petty as nominal semantics. "No thanks."

Tadashi laughs, and Hiro is once again reminded of their talk from last night. It's weird how normal everything is now considering their circumstance. Every so often, he feels a painful twinge in his heart knowing his real brother is still gone; nothing can replace Tadashi, not even a replica from an alternate dimension. But this Tadashi has all the qualities and perks that Hiro's missed these past three months, and it feels good to have a brother again.

"Where is Aya?" he asks between bites.

Tadashi bends over to pet BaoBao. "Taking a nap. She called in sick today so she could watch us, ironically. And before you ask, the others went to class six hours ago. When they told her you haven't slept in fifty-six hours, they left without you. They should be back any minute."

"Wait, what time is it again?"

"It's half past two."

"What, really?!"

"Yeah, you slept for like… how long Baymax?"

"Fourteen hours, three minutes, and fifty-two seconds." Hiro turns to the Baymax, who is standing in the corner next to Tadashi's seat. He didn't even realize the healthcare robot was in the room. He'd been too focused on getting breakfast—which, he now realizes, might as well be lunch.

Tadashi gives him a disbelieving look. "I can't believe you went that long without sleep. Not even my Hiro is that insane, and he stayed up for a videogame marathon for _thirty-two_ hours."

"It's partially your fault."

"No, this is definitely on you. You know I'm a sucker for racing games."

"But you have to admit last night was fun."

"Yeah, it was…" The eldest Hamada brother gulps down the last of his orange juice as the youngest Hamada relishes this moment. This Tadashi really is like his Tadashi; it's like he never even died. It makes him wonder…

"So… this other world you're from… what's it like?"

Tadashi puts down his empty glass and hums, contemplating how to answer. BaoBao looks up at him as if he's suddenly taken interest in the conversation. "Well… from what I've seen so far, it's not much different from this one. The city's the same, the café's the same, and even though I haven't seen the school, I'm sure it's no different than mine. The only things that seem different are… well, this."

"What do you mean?"

"Well, from what you told me two nights ago, you didn't seem adamant to be a part of the school until after the showcase. My Hiro has been at SFIT since early this summer."

"Really? How'd you manage to get other me to apply so early?"

"I actually didn't have do anything."

Hiro scoffs. "Yeah, right. If I know me, it'd have to take more than a few pretty words to convince to me to go to that nerd school."

"I'm serious. You had just finished high school, and all you did was play videogames and sneak out to attend illegal bot fighting matches, which I know you're familiar with."

Hiro looks away, feigning innocence. "I don't believe I know what you're talking about."

Tadashi snorts. "You're not fooling anyone, genius. Anyway, all I did was tell you about the program, and the next day you immediately applied. I'm pretty sure the only reason you did was because I was there, but I was glad regardless." Tadashi suddenly takes on a serious mien. "You and my Hiro—both of you are so gifted. But for a technological genius, you could be an idiot sometimes. Even after joining the school my Hiro wasn't keen on using his talents for the greater good. He pranked his teachers, he didn't get along with his classmates, and he spent most of his time alone. That's not what I wanted for you when you came to SFIT.

"But then you made your microbots for the showcase. You blew every other invention out of the water, including mine, and you did it with a smile on your face. You wouldn't believe how proud I was that day. I finally got to see the world you were going to create..."

Hiro's speechless. Three months ago, he never would have imagined inventing something to help people. The microbots were only a means to an end; he'd just wanted to attend the coolest school ever with his big brother, and those little machines were his ticket in. But after his Tadashi died it was as if he started seeing the world from his point of view. Creating the team made him realize he did want to help people, and he had the means to do so. And if he really does know himself as much as he think he does, the other Hiro will probably reach the same conclusion, if he hasn't already.

A snicker cuts off his revelation, and Hiro sees Tadashi chuckling under his breath. "What?"

"I just realized… my Hiro and my other friends are probably flying around San Fransokyo helping people right now. My little brother's a superhero!" He laughs even harder, and a small guffaw slips from Hiro's mouth. If his Tadashi were here, he'd probably be more angry than happy that his little brother has taken on such a hazardous profession.

Between the laughing, Tadashi coughs harshly, and it quickly turns into a fit. Hiro retrieves the glass of water in front of his plate, offering it to his choking brother. After a few sips, the older boy takes a breath. "Thanks." He wipes away some stray tears caused by his coughing fit, but they continue to fall.

"You okay?" Hiro asks anxiously.

"I'm fine. Don't worry. I'm just… You're both doing something amazing, and I'm glad I get to see it, even in the wrong world. I was afraid my last memory would be of our fight—"

"We had a fight?" This surprises Hiro immensely. He and Tadashi rarely fought. In the past, they've had some really intense debates—mostly about Hiro's perilous, late-night dalliances on Lucky Street—and whatever irate feelings they had for one another afterwards usually dissipated in a matter of minutes. From Tadashi's guilt-ridden face, this had to be the mother of all fights.

"The day of the showcase, Professor Callaghan offered you a position in his lab. You rejected it, and I got upset."

"Was that it?" The guilt on the older boy's face doesn't go away. "Tadashi?"

"Good, you two are awake." GoGo, Wasabi, Honey Lemon, and Fred enter the dining room, interrupting their conversation. GoGo tosses a backpack at Hiro, and the startling girth nearly knocks the teen out of his chair. "Took notes for you. You're welcome."

He glares at her. "You couldn't just hand it to me?" She promptly ignores him as she walks over to Tadashi.

"You okay, Tadashi?" asks Honey Lemon.

Tadashi nods, wiping his eyes one more time to get rid of any remnants of tears. "Yeah. I'm okay."

"Good," says GoGo. "Because we need to talk."


	12. Chapter 11: Of morals and men

**Big Hero 6: ****The Crossover**

**Chapter 11: Of morals and men**

Tadashi sits quietly on Fred's couch as the oldest members of Big Hero 6 brainstorm. Right now, they're facing a giant TV screen that's casting the news. It's a welcome distraction from the uncomfortable tension that's now filling the room. Despite what his friends told them last night, he knows they're still jarred by the fact that he's not their Tadashi. And as he tries to ignore the awkward smiles, fleeting glances, and, in Fred's case, the obvious stare of skepticism, he wishes he at least had one companion that isn't put off by his presence.

As their leader, Hiro is usually a part of these meetings. However, the group unanimously agreed to keep Hiro out of the investigation until further notice since he is still recovering from the 56 hours when he lacked sleep. However, the teen wasn't keen on just lying around and doing nothing for who-knows-how long, so he went to the hospital to check up on his aunt with Aya instead. Tadashi would have joined them, but he knows he'll be more useful here, helping the superheroes (and once he stepped foot in that hospital, he knew Aya and Aunt Cass would team up and lock him in the first vacant room available).

Once they congregated, his friends divulged to him their most recent case, an elusive robbery at Krei Tech. From what he gathered, their thief and Sunfire are indeed the same person, but the college students have yet to make much progress after that.

"So, how much do you actually know about Sunfire?" GoGo inquires. She's the only one who doesn't look at Tadashi like he's an alien, but her lack of eye contact betrays her aloofness.

"Not much, really," he confesses. "I didn't get to know him that well since I was running for my life. The only thing I know for sure is that he needs me for some interdimensional experiment."

"If that's true, why would you go with him?" Fred asks distrustfully. "You're not a double agent are you?"

"Tadashi's not a spy," admonishes Honey Lemon. "But Fred does have a point."

"I didn't know what else to do. He set the café on fire; it was pretty obvious at that point that he was going to do anything and everything he could to get to me. I just wanted to end things before he could hurt anyone else." There's a collective silence as the others exchange exasperated yet droll glances, as if they're sharing an inside joke. Once again, he feels like an outsider among his friends.

GoGo pops her gum. "But that still doesn't explain why he would want you."

Tadashi shrugs helplessly. Nothing has made sense to him since falling into this world.

Honey Lemon puts a comforting hand on his shoulder, but he can still feel the light hesitation as her grip loosens. "How about we just figure out why he stole the portal from Krei. Tadashi's involvement might become clearer if we do."

"And how would we go about doing that? We know absolutely nothing about this guy, besides the fact that he's equipped with a suit that projects fire and allows him to fly."

"He could still be someone working for one of Krei's competitors. It would explain why all of this has been kept under the radar."

GoGo scoffs. "Krei just doesn't want the press to know that he was negligent enough to let it happen right under his nose."

"I don't think Krei is the victim here," Wasabi finally speaks up. He's been on Hiro's laptop this entire time. Tadashi was surprised when he lent it to them; his Hiro would have murdered anyone who even breathed near his laptop. "Remember how clean his secret lab was? It was _too_ clean, and trust me, I know clean." Tadashi exchanges a quaint smile with Honey. Of course Wasabi would brag about something like that. "It would be virtually impossible for someone to steal the portal without leaving a mark. And with Krei's tight-knit security, someone should have been able to stop him before he could get away with it."

"So Krei's obviously hiding something. That's not news." GoGo crosses her arms as she peeks over the burly man's shoulders. "But I guess it warrants hacking into his security feed."

"What?!" Honey Lemon joins them, and she frowns disapprovingly. "Wasabi!"

Wasabi has the decency to look embarrassed, but only a little. "What? Hiro was already on the site. I just so happened to find an exclusive backstage pass into Krei Tech's security system."

Tadashi just watches his black friend as he continues with his morally ambiguous task. He doesn't know much about Alistair Krei, but from what he's heard so far, he's not a fan favorite of the team. The eponymous business man doesn't have stellar reputation in his world, either, as he's known to oftentimes take shortcuts and make shady deals in order to get what he wants. This Krei doesn't seem much different. Although Tadashi wouldn't normally approve of his friend's actions, he's too curious to care at the moment. What Krei doesn't know won't hurt him.

Wasabi pulls out a cord and plugs it into Hiro's laptop. Catching on, Fred grabs a remote and with an audible click, the image on the large screen changes. It's a video, and the paused image shows a lab filled with people. Most of them are scientists garbed in generic white lab coats. Standing in the middle of the lab are two distinct individuals who are dressed as if they should be in an executive office. The well-dressed, smug-looking man in the blue Italian suit can only be Alistair Krei, and the astute woman at his side looking at her phone must be his assistant. Krei is looking directly at the portal, his avid gaze practically gleaming with hunger.

"Krei really did rebuild the portal." Honey Lemon sounds surprised, contrary to the guileless looks on the other's faces.

"Was there really any doubt?" GoGo replies sardonically.

"Look at the corner of the screen." Wasabi points at the top right-hand corner of the TV, where fuzzy digits dot the screen. It's the date the video was recorded. "This happened a week ago."

With another pop of her gum, GoGo joins Tadashi on the other side of the couch and reclines as if she's about to watch a movie. "Let's get this over with."

As the video plays, Tadashi focuses closely on the portal itself. It remains dormant throughout a majority of the video. There's a lot of talking going on, mostly yelling from Krei himself, until finally the portal comes to life. Everyone on camera watches in awe as the swirling vortex inside the machine's apparatus convulses, causing the portal to shake and the room to quake. There's panic throughout the lab as all the scientists try to take control of the situation before blackness starts to creep up from the bottom of the screen.

"… Is that it?" GoGo almost sounds disappointed, and Tadashi shares the sentiment. He'd really hoped this video would give them some answers.

In the background, Tadashi hears a few clicks and frustrated murmuring, but his eyes never leave the screen. "That's the only video I could find in the secret lab. The cameras must have been disabled after that."

"Dudes, I think I figured it out." Fred, who has been surprisingly quiet for a while, stands up and turns to his friends. His face is the epitome of profound insight. Suddenly, he points to the Baymax, who has been looking at Fred's superhero paraphernalia from the back of the room in silence. "Baymax, you scanned Sunfire the other day, right? Is there some sort of DNA match thingy you can do to find him in the city?"

A pregnant pause. "There is no genetic match."

"I knew it!"

Tadashi exchanges a confused glance with the rest of his friends, for once feeling more included now that he's not the only one out of the loop. "Care to share with the rest of us, Fred?"

"I know how Sunfire got into Krei Tech!"

A collective silence follows. Finally, GoGo rubs a hand over her face tiredly. "I'm going to hate myself for asking this: How Fred?"

Seeing no objections, Fred fires himself up for one hell of an exposition. "Okay, so remember what Tadashi told us yesterday about falling through the portal when he ran into Sunfire? Well… what if he wasn't the only one?"

"Are you saying that Sunfire's from an alternate world," Honey infers, "like Tadashi?"

Fred nods so fervently Tadashi's afraid his head will fly off. "Think about it! This video took place a week ago. That's plenty of time to take the portal and set it up in some secret location somewhere in San Fransokyo, and this city's got abandoned warehouses for _days_! Plus with all that equipment, he would need a team to transport it from the lab. Sunfire's not working for _Krei_; Krei is working for _Sunfire_!"

"But why would Krei willingly give him the portal?" asks Wasabi.

"He wears a suit made of _fire_!" Nobody can argue with that logic. "Then I remembered when Callaghan rebuilt the portal, it was just as unstable as when they first tested it. He didn't fix any of the mistakes they made when he lost his daughter. Suddenly this fiery fiend has come out of the shadows, snatching up pieces of a puzzle that our former nemesis couldn't solve. A few days later, Tadashi returns, and now Sunfire's after our resurrected ally. Which means…"

Tadashi can practically feel his cranial lightbulb flicker to life. "Sunfire must have found a way to travel through dimensions."

"EXACTLY! It's just like volume three issue seven of Captain Dandy!"

Wasabi gawks at them both. "Wait, what just happened?"

Honey laughs nervously. "Should we be concerned that Fred's making more sense than usual?"

"It does sounds crazy, but so does interdimensional travel," rejoins GoGo. "And Fred's come up with crazier stuff. It's the most logical explanation anyone's made so far. Sunfire may still be a mystery to us, but we can't deny that he's clever. His genetic signature doesn't match anyone in the city according to Baymax, so it can't have been someone working for Krei or his rivals. And if we fill in the blanks from the video, he may have _literally_ come out of nowhere. If he has the technological know-how to repair the portal itself, then he knows exactly how it works. He knows what he's doing."

"But wouldn't we know if there was a working portal somewhere in San Fransokyo?"

"He's probably still missing a few essential pieces. He can't get it to work unless he has all the proper equipment."

"And Tadashi is one of those pieces!" Fred jumps out of the way of a flying couch cushion.

"In that case, we're working on limited time." Tadashi stands as he addresses his friends. As his eyes sweep the room, he notices that their expression are less haunted. At the moment, they're no longer looking at some interdimensional clone of their deceased best friend; they're just looking at him, Tadashi. "There's no telling why Sunfire needs me specifically, but we can assume that he's still missing some components needed to make the portal function properly. I don't remember much when I was in the other dimension, but I think my time there may be the reason why he wants me. And unless I turn myself in to Sunfire and let him experiment on me—"

"Which is definitely not happening."

"—we're going to have to figure out how to stop him before he can finish building the portal."

"And I don't want to be that guy," Wasabi holds a hand up reluctantly as if they're in a classroom setting, "but we still have to study for finals, so the sooner we find Sunfire, the better."

The reminder of school suddenly has the other members of Big Hero 6 groaning. Tadashi hasn't even thought about school since first entering this world. If it's been three months since his alternate self died, then how much time has passed in his own world?

As the other begin to deliberate their next move, Tadashi thinks back to that moment when he fell. The familiar ache that companies the act of remembrance returns, and he rubs his aching temple. It seems there's still something in his memory that he can't find, and it may be the key to all of this. Perhaps there's someone else who can help them figure it out. There's only one person who comes to mind, but Tadashi almost doesn't want to dredge it up. With their shaky history, he's not sure how the others will agree with his idea. But if they want any insight of Sunfire's plans, then they need an expert.

He clears his throat to recapture his friends' attention. "So, I think I know someone else who can at least give us an idea of what happened to me in the other dimension."

"And who might that be?" asks Honey.

He emits a sheepish smile, scratching his cheek. "Where's Callaghan staying nowadays?"

**O—O**

Damn Big Hero 6!

He was so close; the solution to his dilemma had been literally within in his grasp! But his friends—_those damn superheroes_—ruined his plans once again!

It was supposed to be so simple. Right after the younger brother left for school, the aunt was supposed to open the café, leaving the boy alone, and he could grab him, leaving no one the wiser. But the aunt hadn't opened the café, and the boy wasn't alone. They spent the whole day together. This made things difficult, but he refused to let this little setback deter his plan. It was time to suit up and do what he did best:

Light things up.

For anyone else, this job wouldn't be easy. That kitchen was a fortress; not even a nuclear explosion could knock the roof off this little café. But with some carbonic acid and a tiny hint of hydrogen peroxide, the kitchen would light up with ease. The homemade concoction he developed was a colorless, odorless gas that lit anything it touched, and when it was put out with water, it immediately dissolved; it was completely untraceable. The flames would spread quickly. Hopefully the two occupants would notice it before it was too late. He needed the boy alive, after all.

He waited above the building, sitting behind the giant calico motionlessly waving at the people below. After one minute, the entire first floor was covered in smoke, but no sign of either the boy or his aunt. As the smoke escaped the doors, a crowd steadily grew outside the café. This made him nervous. Surely they would have noticed it by now? Finally, aunt and nephew ran out of the café, breathless and sooty.

A pair of bystanders in the crowd helped them on the curb on the other side of the street. The boy himself looked unharmed, but he couldn't say the same for the aunt. A nasty gash bled profusely from her arm, and her skin was slowly getting paler. His intention wasn't for anyone to get hurt, but there were no guarantees once he lit the kitchen aflame. The boy must have noticed her injury as well because he immediately scanned the streets. He looked ready to murder.

Perfect.

He immediately took flight. He wanted the boy to notice his presence, to let his rage take precedence over common sense and take off after the villain who put his family in harm's way. And just as he predicted the boy left the scene, albeit hesitantly. But once the ambulance arrived, he became more surefooted; his aunt would be safe, and so would everyone else.

He stopped on top of a building a few blocks away. Not a moment too soon, the boy entered the alley between this building and the adjacent one. His breathing was extremely heavy, his face pallid, yet fiercely determined.

"Hey! Your beef is with me, not my family! If you want me, you got me! Just keep them out of it!"

He had to admire that boy's tenacity. Even after inhaling an innumerable amount of smoke, he still had the energy to run here and shout at his invisible stalker. And now he was offering himself, right on a silver platter. It was an attractive offer: he'd have the boy, no one would get hurt, and he could finally finish his experiment.

Who was he to refuse?

He flew down to the seething boy and proffered his hand. He would agree to these terms. On two conditions.

"No more running. No more hiding."

Looking into the boy's eyes, he saw indecision, but it was quickly replaced with firm resolve. His hand was so close, he could just reach out and take the boy right now. But he held himself back; it wouldn't do to scare him off and break their momentary truce. This was it. This was the end. He would finally accomplish his goal and reach beyond the boundaries of space and time. He could already feel the interdimensional plane bending at his whim…

Suddenly, a yellow streak broke their accord, disappearing just as quickly.

"Hold it right there, villain!"

And just like that, his dreams were stomped, and in the form of a three-eyed blue and orange monster.

But that streak and the creature that followed it couldn't have come from nowhere. Looking up, he saw a giant red suit of armor floating above. Two more figures were attached to it, one yellow and the other violet.

It was those superheroes Krei warned him about: Big Hero 6.

"Finally! An adversary I can contend with! Hath at thee, fiery fiend!"

From the muffled voice, it was obviously a man in a costume—a high-powered flame-throwing costume with high jumps and flexible limbs. It was actually a rather impressive design, but he had no time to marvel the engineering of this strange beast, not when it was standing between him and endless possibilities.

The fight lasted much longer than he anticipated. The monster was much faster than it looked, and his flames matched his in power and intensity. But this hopping fool lacked any combative skills; he was just throwing the flames around and simply hoping for the best, which left him with many vulnerabilities. So whenever the beast stopped breathing fire, he would come in and hit him with everything he had. He was about to go in for the finishing blow when something hit him in the head, jarring his vision. In the next instant, a yellow streak glided up to the three-eyed monster, helping him up. The yellow hero held up her arm, and a yellow disk reattached itself to her. It resembled the disks attached to her ankles. Upon closer inspection, he saw that her feet weren't even touching the ground. Magnetic suspension. How the hell was he supposed to combat that?

Once the heroes were both on their feet, they immediately teamed up on him. If this fight prolonged, he'd run out of power, so for the time being he retreated. He knew the bouncing blue monster was following him, but his main concern was the boy. Unfortunately, when he returned to the alley, he and the violet and red heroes were nowhere to be found.

Damn those heroes! What the hell were they even doing anywhere near the café, anyway? There was no way something as menial as a _house fire_ would attract the attention of a superhero team! This wasn't how today was supposed to turn out! His plans, ruined…

No, not yet. He refused to let this… _minor inconvenience _get the best of him.

The red hero couldn't have gone far. More than likely, the boy was taken to the hospital to be treated for the smoke inhalation. And so that's where finds himself several hours later, dressed in his civvies. He asks for the aunt—Cass Hamada, his dear cousin, he told the nurse at the front desk—and heads to her designated room. Peeking through the blinds in the window of the room, he sees her holding her arm, which is now bandaged, and worrying her lip. He turns away when he sees a doctor approach and listens in as he talks to the aunt.

"Has he checked in yet?"

"I'm sorry, Ms. Hamada, but no one's seen him."

"B-B-But those heroes—those heroes promised they'd find him. He should be here!"

"I don't know what to tell you. Your nephew hasn't been checked in yet. I'm sorry."

This isn't good. If they didn't bring him here, then where the hell is he? Do these heroes have some sort of underground medical headquarters or something?

It doesn't matter. The aunt is here. The boy will come here to visit her eventually.

He makes to leave when the sudden sound of sobbing reaches his ears. He turns back to the window and sees the aunt crying into her hands. It makes him feel… unsettled. The longer she cries, the harder his heart clenches. He should just leave; she is no concern of his. She's just one of those obstacles, a victim who was at the wrong place at the wrong time…

In the end, he stays. He listens to her lamentations, even though there is nothing he can do to help her. He stays until he is asked to leave, but the cries still haunt him all throughout the night.


	13. Chapter 12: Things I do for superheroes

**Big Hero 6: ****The Crossover**

**Chapter 12: The things I do for superheroes**

Hiro leans his head against the car window, his eyes unfocused even as they pass the charred remains of the Lucky Cat Café. The fight he and Tadashi supposedly had has been on his mind since he left the mansion, and he still can't comprehend it. The other Hiro had rejected the other Callaghan's offer to work in his lab; the circumstances seem similar to the time when he refused to sell his microbots to Krei. His Tadashi supported his decision, but then again, Krei proved to be an underhanded businessman who took shortcuts and didn't care who got hurt in the end. He wonders if the other Callaghan had similar intentions with the other Hiro's invention, and if the other Hiro had the intuition to deny the greedy professor a chance to use the microbots for evil. So why did the other Tadashi get mad at the other Hiro for his choice? Sure, it sounded like a once in a lifetime opportunity, but his alternate self wouldn't just dismiss Callaghan's offer for something petty… would he?

Hiro made a lot of foolish mistakes before his college days, and he knew that he got on Tadashi's nerves on more than one occasion. The other boy was just better at hiding his frustration. But the other Hiro must have crossed a line to have angered Tadashi to the point that he acted in a way that made him feel this long-standing guilt. Was it something he said, or something he did? Whatever is was, Tadashi regrets it tremendously. And if his alternate self is really at fault, then he really doesn't deserve to get Tadashi back…

"… Earth to Hiro. Can you hear me all the way from Uranus?" Hiro swivels his head to see the prying look Aya is giving him. Her arms are folded, which alarms him, until he notices that the car is in park. When Hiro looks out the window again, he spots the entrance to the hospital. He was so lost in thought he hadn't even noticed they arrived.

"What?"

Aya rolls her eyes at the pathetic reply. "It seems someone didn't get enough sleep last night. I've been trying to get your attention for the past five minutes."

"Hey, I slept a solid twelve hours according to Baymax, and then some."

"Well, sleep or no sleep, you're acting like a complete space cadet."

He pouts, shoving his hands into his pockets. "Whatever."

Again, the young woman's eyes roll as if to say, "Teenagers."

"Does this have anything to do with Tadashi? I thought you two were starting to act normal around each other again… Then again, I've only known you all for less than two days, so I don't really understand your dynamics. Plus with this superhero stuff and the alternate universe hoopla—"

"Don't worry. This is pretty normal… except for the alternate universe stuff. That's a new one for us. But me and Tadashi are good. It's just… Tadashi said something to me that I can't stop thinking about."

"… And that would be…?"

Hiro's silence apparently warrants a punch to the shoulder. "Ow! What the heck?"

"Look, Hiro. I know that I'm technically still a stranger to you. It's flattering that you trust me enough to take care of Tadashi without the proper medical equipment or a ready staff on hand to take over in case something goes wrong—don't give me that look, he's just asthmatic, nothing to worry about—and I'm eternally grateful to Fred for letting me stay in the most expensive house I've ever set foot in until this whole thing with Sunfire blows over. So while I'm still around, I'd appreciate it if you'd take advantage of my services." She looks Hiro straight in the eye, her gaze earnest. "Talk to me."

Without breaking eye contact, Hiro casually reaches for the door handle only to be met with resistance. Turns out she put on the child safety locks while he was still stuck in his head. The corner of Aya's mouth upturns slightly when she witnesses his failure to retreat from the situation. He has no choice now. "… We had a fight. The other me and Tadashi, that is. We fought the day he vanished through the portal. It's just a little hard for me to wrap my head around."

"Did you and your Tadashi never fight?"

"We've had some intense debates, and there was one incident when I accidentally blew up his bike." Aya raises an eyebrow at this. "I was a bored five-year-old genius—give me a break. Anyway, from what Tadashi told me, it was a serious fight. Like, maybe even more serious than just slinging hurtful words at each other. He said he was afraid that his last memory would be of their fight. It's probably ridiculous that it's bothering me so much. It's not like _I'm_ the one who was arguing with him. AH! What's wrong with me?!" He slaps his hands over his face. The exclamation causes the Jindo in the backseat to whine, as if he's sympathetic of Hiro's dilemma.

"Maybe the idea of Tadashi never getting a chance to apologize to his Hiro is what's bothering you."

"What do you mean?"

She shrugs. "Well… since you and your Tadashi practically never fought, the very idea is so unfathomable that you're probably going to keep thinking about it until you can actually do something to fix whatever problem… other you and… other Tadashi had." Aya shutters. "Yeesh, that's going to take some getting used to."

"How would I go about doing something like that? In case you forgot, this Tadashi is from _another universe!_"

"Trust me, I will _never_ forget that fact. Use your head, genius. Tadashi got here because of the portal, right? If someone got it to work once, then it can definitely be fixed again. And if you catch this guy—"

"When."

Aya rolls her eyes for the third time. "Fine. _When_ you catch Sunfire, you'll have the means to send Tadashi back. And before you lecture me on the quantum mechanics of traveling through what's basically a distended black hole without knowing exactly where Tadashi came from, I know that if anyone can figure it out, it's you eggheads."

Hiro's mouth is agape, and the nurse smirks at the reaction she evoked from the teen. "Aren't you a nurse?"

"Just because I work in medicine doesn't mean I don't know anything about other fields of science, thank you very much. You can't get into med school without taking at least a year of physics, and I happened to gain a certain interest in it. Plus if you think about it, the theoretical mechanisms of quantum physics aren't much different from the physiology of the brain…" She pauses and glances at the teen beside her, who is now completely in awe. Clearly, there's more to this nurse that goes beyond a measly medical degree. "A-Anyway, we're getting off track! This therapy session is about you, not me."

"Sorry for distracting you," Hiro replies sarcastically. "What you were saying before makes sense, but… Tadashi never said anything about wanting to go back."

"Yeah, but he has to go back eventually. He has another little brother and another weird group of friends who probably miss him very much." Silence fills the car once more, and the weight of its meaning is heavily culpable. "Oh… Hiro, you know he can't stay here, right? He's not—"

"I know he's not my brother!" The pinprick of oncoming tears lingers at the corner of his eyes, but Hiro suppresses them. He refuses to cry about this again. He has to remind himself of that fact over and over again whenever he sees Tadashi walking around, smiling, laughing, filling that void that everyone's missed these past three months, as if the real Tadashi isn't currently buried six feet under. He doesn't need someone else to tell him that. It's not like he's in denial.

"… But it still hurts. Knowing my brother is still dead. Knowing this other-dimensional clone isn't and will never be him. Knowing he has to go back no matter how much I want him to stay. It's all extremely painful, and it's going to feel so much worse once he's gone again. Aunt Cass doesn't even know about any of this, and now I have to go in there and lie to her face! What am I going to tell her when Tadashi leaves? 'Sorry, Aunt Cass, but the nephew who we thought was dead and miraculously came back into our lives is gone again because, turns out, he wasn't even from our universe. So good news! Our Tadashi's still dead, so there's nothing to feel sad about'!" Hiro is practically panting at this point, and the tears he's worked so hard to hold back fall down relentlessly. And just like that, several hours of progress and accepting the situation for what it is, gone in a matter of seconds. "I can't lose him again! _I just can't!_"

All of a sudden, Hiro is pulled into a secure embrace. It's not as warm or familiar as Tadashi's hugs, but it's comforting all the same. He leans into the hold, his tears gradually seeping into Aya's maroon hoodie. She rubs his back in concentric circles, and he relishes the soothing touch.

"I don't want him to leave… but the other Hiro needs him more. And as long as he's here, then whatever issues they have will never be solved."

"Congratulations. You've reached a breakthrough."

Hiro chuckles, and a hiccup escapes his lips. "Sh-Shut up…" Pulling away, the teen sniffs up the residual snot and wipes away the remainder of his tears. "And thanks. I know this whole situation is weird, especially since you're new to the group. Please don't tell the others about this."

"Don't worry. Nurse/patient confidentiality prevents me from speaking about this with anyone." She squeezes his shoulder reassuringly and gives him a placating smile. Something wet bumps his cheek, and Hiro reaches back to pet the emotional support canine. "But you should think about telling your friends. I'm sure they'd want to know how you feel."

"I'll think about it… You sure know a lot about this stuff for a nurse."

"Well, I was a SFMI student."

"Was? As in past tense?"

"Yep."

"And not right now."

"Nope."

"Why not now?"

"Oh no. This therapy session is officially over. Let's go see your aunt."

"Wait a second!" Hiro grabs her wrist before she can make a run for it. "We sat here talking about my personal stuff for the past five minutes. And I cried for, like, the second time within twenty-four hours! And I _hate_ crying! It's only fair that you at least share something personal about yourself." Aya bites her lip, looking insecure. She has no reason to tell him anything, and Hiro knows that she can pull away anytime she wants; he's just a shrimpy teenager, after all. But the fact that she's still in the car with him means she's at least contemplating it. "We may have only known each other for a short time, but we've been through a lot together. You're not just the nurse taking care of my brother anymore. You're a member of the team… and our friend." He eases his grip, offering an amicable smile. "Talk to me. Please."

Aya finally settles back into the driver's seat, huffing grudgingly. "Fine. You and your brother sure are nosy." She crosses her arms again and avoids eye contact as she shares. "If you _really_ have to know… a while back, my mom got sick. She couldn't work anymore, and I couldn't afford to go to a fancy university _and_ pay for her medical bills. So long story short, I transferred to an online nursing school, and now I have a crappy job at a crappy clinic in the crappiest part of San Fransokyo. The end."

"… Wow. I… don't know what to say."

"Well don't say sorry. I heard enough of that when my mom first got admitted at San Fran Gen."

Hiro shifts uncomfortably in his seat. He's never had to comfort anyone before, and that seems like the last thing Aya wants. He's sure she's dealt with enough grief due to her mom's illness. But looking in the rearview mirror, he sees a peculiar sheen in her hazel eyes. If Tadashi's death has taught him anything (besides the importance of friendship and forgiveness and yada, yada yada), it's that there's always one surefire way to make someone feel better. She may not want it, but she needs this.

Hiro grabs her around the waist, and Aya hugs him more loosely. As if feeling left out, BaoBao jumps on Hiro, who laughs and squeezes him into their awkward car hug. "Okay, okay. That's enough. Let's get inside before hospital security asks us to leave." Before she can open the door, she turns back around and glares at Hiro. "Nothing leaves this car."

He smiles cheekily. "Of course not. Nurse/patient confidentiality, remember?"

**O—O**

"Hiro! It's so good to see you!" Cass pulls her nephew into an air-depriving hug as soon as he's within reach. It seems to be a regular thing with these people. "You better have been studying because I can't think of any other reason it's taken you this long to visit your poor, sick aunt in the hospital!"

"Can't… breathe… Aunt Cass…!"

Aya rubs her arms subconsciously as she stands in the doorway, feeling like an interloper once again in this strange but touching moment. But she doesn't mind staying silent after the heart-to-heart between her and Hiro. With his impressive resumé, it's easy to forget he's just a kid. He's definitely felt this way for a while and hiding it from his friends and loved ones has to be a tiresome burden. Aya's heart went out to him when they were in the car, and while she was holding him in her arms, she knew that wouldn't be a one-time thing.

Cass finally releases his nephew, who scoots back in his chair a safe distance away to catch his breath, and addresses her other visitor. "Aya, thank you for bringing my knucklehead of a nephew. You've been a godsend these past few days."

Aya hugs her arms closer to her abdomen bashfully. "I'm just doing my job, really."

BaoBao sniffs the older woman's hands, and she scratches his ears, eliciting a happy bark. "Speaking of knuckleheads, where's Tadashi? Those heroes promised to find him, and he hasn't been checked into this hospital at all."

Aya and Hiro exchange a brief, panicked glance. Looking at that sweet, naïve face, she understands what he was saying about lying to Cass. Such a blasphemous thought forms a knot in her stomach. This is the same master barista who invented the savory, life-giving coffee drink known as the Lucky Catppuccino. She'd never forgive herself if she uttered a single fraudulent word to this woman.

"That's because the heroes took him to Aya's clinic instead!" Aya gawks at Hiro. What the hell is he doing?

"Why'd they do that?" asks Cass, perplexed.

"Because it was closer! And now he's fine. We're staying at Fred's place for now." Aya kicks Hiro while Cass isn't looking. Hiro grimaces and shrugs helplessly. She rolls her eyes for the umpteenth time that day. There's no way she'll believe that.

"Oh. Well, that's good. I'm glad he's okay." Oh. That was easy. Turns out honesty is the best policy. "But he was acting really strange when he ran off. Maybe he should get checked in just in case."

"I really don't think that's necessary, Aunt Ca—" The jingle of a cell phone cuts off Hiro, who swiftly excuses himself and leaves the room to answer it. Leaving Aya to deal with his skeptical aunt. That sneaky little turd.

Taking the seat Hiro previously occupied, Aya offers the older woman her most sincere smile. "I'm sorry about the café, Cass."

Cass waves the worrisome sentiment away. "_Psh!_ There's no need to worry about that. Thank goodness for insurance, am I right? But that fire was peculiar. I haven't used the kitchen in the café since Tadashi's return, and I always make sure that everything's off before closing up. The firefighters couldn't find what started it, either. It was as if the fire just spontaneously appeared. Strange, huh?"

Aya fiddles with a strand of hair behind her ear and finds a sudden interest in BaoBao's whiskers. "Y-Yeah, that is strange." As strange as her oldest nephew being from an alternate world, her younger nephew being the leader of a superhero team, and their fiery nemesis who has an unhealthy obsession with the former. "S-So how much longer do you have to stay here?"

Cass thankfully goes along with the change of subject. "Just one more day, thank goodness. As a cook, I loathe to stomach the garbage they pass off as food here. I swear if I see one more cup of canned peaches I'm gonna—"

"You WHAT?!" The sudden interjection makes the two women jump. Aya enters the hall to see Hiro on the phone, red-faced. The teen doesn't seem to notice the glares being sent his way from his exclamation. Aya's never seen him so mad. "… We're coming back."

She closes the door just as he hangs up. "What was that?" asks Cass.

The answer comes in a form of the irate teen. "We gotta go," he says to Aya.

"What happened?"

He ignores her as he walks up to his aunt. "Sorry, Aunt Cass. Something's come up. I'll come back as soon as I can." After pecking her on the cheek, Hiro rushes out of the room.

"What's going on?"

Aya bites her lip for the umpteenth time that day. "I wish I knew." And with those cryptic words, the nurse runs after the teen, apologizing to any doctors and nurses she passes on the way. "The things I do for these people…"

**O—O**

Twelve hours later, he finds himself waiting at the hospital once more, standing vigil near the aunt's room. At this point, it's ridiculous how long he's waited for someone to visit her. Not even the younger nephew has come back. He should have heard about the fire by now; why isn't he in there comforting his poor aunt (not that he cares)? And where the hell is his brother?!

The longer he waits, he realizes, the more suspicious he looks. The nurses keep giving him weird looks, and one of the passing doctors looks like he wants to say something to him. To avoid that uncomfortable encounter, he takes a moment to go to the cafeteria and get a coffee. As he walks back, he's met by an unpleasant shout.

"You WHAT?!"

He walks faster to the scene (once again, not because he's worried about the aunt) and arrives just in time to see a scrawny boy running out of hospital wing, followed by a young woman and a tan and black dog wearing a red vest.

"I'm so sorry, sir!" she apologizes hastily.

As she brushes past him, something falls on his left foot. A blue dog face stitched on brown leather smiles up at him. She dropped her wallet. Picking it up, he thinks about going after her and returning it (he may be a villain, but he's no monster). He abruptly follows the rushing pair of adolescents leaving the hospital, making sure to keep his strides long and even so as not to appear conspicuous. Once outside, he sees the girl slip into the driver's seat of a blue sonata before driving out of the parking lot. It's an old vehicle, but not uncommon. He's only seen one this week…

And then it hits him.

It's the girl.

The same girl who helped the boy escape his clutches, the one who had originally foiled his plans.

Which means the boy she's with is the younger brother.

What are the odds that that same girl would be here, with the younger brother of the boy she drove off with? And the younger brother—he was talking to someone before he abruptly ran off. It had to be the boy. They both know where he is.

This is it. This is how he'll finally succeed. If he can't find the boy, then the boy will have to come to him. Then he'll be on his way to the realm of infinite possibilities.

And this time, nothing will get in his way.

He takes his leave, a new plan brewing in his mind. Stuffing the wallet into his coat pocket, he pulls out his phone and presses the speed dial. As soon as the receiver picks up, he cuts to the chase. "Krei, I need you to do one last thing for me…"


	14. Chapter 13: A space-time anomaly

**Big Hero 6: ****The Crossover**

**Chapter 13: A space-time anomaly**

Tadashi stands in front of the building, suddenly feeling squeamish. San Fransokyo Correctional Facility looms over him in big, fat, bold white letters. As he and GoGo wait for Wasabi to park his car, he stares ahead through the gate that leads into the prison. The last time he saw Callaghan he was dressed as the supervillain known as Yokai. Tadashi didn't understand his need to be so incognito. Granted what they were doing wasn't very legal, but the villainous wardrobe was over the top in his opinion. But as long as they got Abigail back, he went along with whatever eccentricities Callaghan had.

He wants to believe this Callaghan had similar intentions, but the bold, capitalized letters that spell out the name of the prison say otherwise.

"You doing okay?"

Tadashi tears his eyes away from the gate to address his stoic friend. "Yeah, yeah. I'm good. Peachy, in fact." GoGo raises an eyebrow at him. "Okay, I'm not peachy. This is just…"

"Weird?"

He scoffs. "That doesn't even begin to describe this. And I know that's not saying much considering me being from another universe is weird in itself, but never in my wildest dreams would I have imagined visiting one of my professors at a prison. When I last saw Callaghan, I was helping him build the portal. The only thing we did wrong was build a hazardous interdimensional machine on campus without permission. Not to mention I had to hide this from my friends and family. And I know that sounds bad, but all we were trying to do was save a little girl."

"Little girl?"

"Abigail."

GoGo pops her gum. "You really are from a different world, aren't you?"

"Why? Does this Callaghan not have a daughter?"

Before she can answer, the gate to the prison opens. A young woman steps out and stops in front of the college students. And although Tadashi's never seen her in his life, she looks familiar.

Turning to GoGo, she smiles. "GoGo! It's good to see you."

"You, too, Abigail. How have you been?"

Tadashi inadvertently gawks at the brunette. _This_ is Abigail?! But that can't be right! The Abigail he knows is a six-year-old girl with blonde hair and pigtails! Well, some people's hair changes color as they grow up—but that's not the point! This world is more backwards than he initially perceived.

"Are you one of my father's former students?"

Tadashi tries to smooth over his surprised expression into something more pleasant, but it feels more like a grimace. GoGo comes to his rescue and pulls the strings on his borrowed hoodie, covering his face. Their Tadashi is still dead, so it wouldn't do for someone to recognize him and freak out.

"He's a transfer from New Kyoto Tech," GoGo lies effortlessly. "He just happens to be an admirer of your father's work."

"Oh. Well, I'm glad some people still see him as a respectable scientist." Abigail's smile melts away and is quickly replaced with a grimace of her own. "The university has asked me to return all his academic awards, and they sent me the picture that was hanging in the foyer of the robotics lab."

GoGo frowns in sincere sympathy for the older woman. "Sorry, Abigail."

"Dad founded the Laws of Robotics. He's helped people all over the world with his inventions. Now whenever someone even mentions the name Callaghan, the only thing they see is a villain." Abigail's hands squeeze her purse. "And it's all my fault."

"No, it's not." Tadashi pulls his hoodie back down, despite GoGo's warning glances. "You shouldn't blame yourself for any of this. Science is full of risks. You both knew that going in. Whatever choices he made, it's his responsibility to shoulder those burdens, not yours." He thinks back to the moment right before he got sucked into the portal, when he saw that the intruder was Hiro, and he was five seconds away from losing him forever. He doesn't regret trying to help Callaghan, even if he can't see Hiro again. He'd do it again in a heartbeat if it means Hiro and Abigail are safe. "I know Callaghan's not truly bad. Yeah, he did bad things, but only because he lost something truly precious to him. I'm sure he would have given away all his awards if it meant getting you back. I know I would."

Abigail stares at the stranger, astounded. But ever so slightly, the scowl on her face transforms into a grateful smile, her blue eyes glistening with tears. "Thank you. You don't know how much it means to me to hear someone say that." The moment is disrupted by the buzz of a vibrating phone, and the young brunette breaks eye contact to check her cell. "I've gotta run. It was nice meeting you. And it was great seeing you again, GoGo." With a wave goodbye, Abigail walks into the parking lot.

GoGo turns to him, her expression once again impassive. "I'm finding it harder to believe you're not our Tadashi."

"Why's that?"

"Because he would have said the same thing. Tadashi didn't hold grudges, and I'm sure he would've forgiven Callaghan despite everything he's done."

"So Callaghan really started a fire just to steal Hiro's invention? Why didn't he just ask for help?"

GoGo crosses her arms and leans against the gate. "No one knew if Abigail was even still alive. After she got lost in the other dimension, Callaghan went nuts. Apparently he'd been plotting his revenge against Krei for a while because the incident happened before the showcase. He was beyond reason by that point. None of us could have known, but if we had maybe we _could_ have helped…" Her hands dig into her arms, and Tadashi winces. No matter how emotionless GoGo appears, she can still be easy to read.

"I'm sorry, GoGo. I shouldn't have asked you guys to take me here."

She punches his arm. "Don't apologize. Callaghan's the only one who can help us, so it's not like we have much of a choice. Besides, you're our friend. It doesn't matter what dimension you're from. We'll always be here for you, Tadashi."

The young man rubs his bruised appendage. "Ow. And thanks."

A few minutes later, Wasabi finally joins them. "Took you long enough," gripes GoGo.

"I couldn't find a good spot!"

"There's, like, ten other cars here. There are plenty of good spots to park."

"I have a system for everything, GoGo! You know that! Now who's ready to visit to our convicted professor?" The rhetorical question is met with a wry smile and the resounding pop of bubble gum. "Right. Let's go in, I guess."

"Do you guys visit Callaghan often?" asks Tadashi.

"Only a handful of times," admits GoGo. "Except for Hiro."

"Yeah, Hiro hasn't seen Callaghan since they arrested him. Before you… came into our lives," Wasabi shoots him an apologetic smile, "Hiro wouldn't even utter his name. He's not mad at Callaghan anymore, but I don't think he'll ever forgive him for what he did."

Tadashi can't say he blames him. He had told Hiro not to blame Yokai before he fell, but even he would have a hard time not seeing a masked stranger in an overcoat as the villain, especially if he was partially responsible for trapping him in an alternate world. "Does he know that you guys come here?"

"Yeah, and we invite him every time. But he never comes."

"So what will he think when we tell him I came here?"

"He'll probably go ballistic," answers GoGo. "But he'll get over it."

Once they enter the prison, the college students make their first stop at the front desk, where they leave behind any prohibited items. When they have to show their IDs, Wasabi and GoGo show their driver's licenses. Tadashi is asked to put his hood down when he shows them an old student ID that belonged to his alternate self. He doesn't ask how they managed to snag it from Hiro, but he has a feeling that it was GoGo's doing. The guards lead them through a series of halls until they're in a completely isolated area.

"They're keeping him in solitary confinement?" Tadashi whispers in astonishment.

GoGo gives him a look as she pops her gum for the umpteenth time. "He built a portal that destroyed the Krei Tech building and nearly swallowed up San Fransokyo."

"… Okay. Point taken."

They finally reach the door. And on the other side is Callaghan.

"Only one visitor at a time."

Wasabi and GoGo move aside, leaving Tadashi to face this task alone. "I-I guess I'm going in. See you guys in a few minutes." He doesn't take a single step. He reaches up to grasp the comfort of his hat only to be met by his unkempt hair. Oh, right. His hat is still in the other world.

A hand claps itself on his shoulder, and he looks down to see GoGo giving him a reassuring smile. Well, what's considered a smile in her case. "We're not going anywhere, Tadashi. We'll be right here waiting for you." Wasabi gives him a thumbs-up. With his friends' encouragement, Tadashi finally takes the first few steps inside Callaghan's cell.

It's dark, except for the square of light in which the former professor resides. The man himself has his back to the entrance, and he's leaning over in his chair, big, calloused hands running through salt-and-pepper hair. The walls are a dark, hoary color that bleeds black when the door closes behind him. The sound stops the prisoner's fidgeting, and slowly he turns around. His wrinkly eyes crinkle as they try to discern whoever has entered the cell. "Who's there?"

Little by little, Tadashi shortens the distance between him and Callaghan. As he gets closer, he can just barely make out his own transparent reflection. Apparently Callaghan is considered too dangerous to be kept in a normal jail cell. Once Tadashi is in the light, the older man is on his feet. His face takes on a pallor complexion, his eyes wide as if he's seeing a ghost. Which, Tadashi thinks, is probably exactly what he's experiencing. "T-Tadashi? But I thought I… How is this possible?"

"It's not what you think, Professor."

Callaghan suddenly shrinks into himself, sinking back into the chair where he was previously wallowing. "I don't deserve to be called that, especially by you." It breaks Tadashi's heart seeing someone he's admired for so long look so broken. But he has no time to make him feel better. The other Tadashi is still dead, and there's nothing anyone can do about it.

"Professor, I'm not Tadashi."

Callaghan looks up again, befuddled. "What?"

"I mean, I am Tadashi, but not this world's—look, it's a long story. I got sent here by Yokai—the other you—but not on purpose. I was trying to help you—other you—rescue your daughter, but the portal was too unstable and I got sucked in. Now I'm here and there's another villain—Sunfire—out there who's trying to rebuild the same portal that got me here, and we—me and Big Hero 6—think that he needs me in order to make it work properly. Long story short, we need your help to catch the guy before he does something drastic."

Callaghan stands and his eyes roam the younger man's form analytically. He crosses his arms, intrigued. "An alternate world, huh? So someone figured out the Einstein field equation for interdimensional travel. So who is this… Sunfire?"

At first, Tadashi is too lightheaded to reply. He should have known someone as erudite as Callaghan would be more open-minded about this. He barely even reacted when he mentioned he's from another world. Callaghan just accepted it as fact. It's one of the things the young man admires about him. Right now, the older man's eyes retain a sharp glint that Tadashi recognizes as scientific curiosity.

"We don't know his real identity. All we do know is that he's extremely clever and he knows his stuff. He stole the portal's apparatus from Krei Tech and who knows what else. He also rebuilt the portal by himself and somehow figured out how to get it to work, hence…" He gestures to himself.

Callaghan plants a fist under his chin pensively. "What did you do when you were helping the other Callaghan rebuild the portal?"

"I assume the same thing you did when you rebuilt it over the Krei building. We were just trying to make it functional enough to retrieve Abigail, not fix it. It was too unstable for anything practical. But then I got trapped there for… I don't even know how long. I think time works differently in the other dimension than it does in other realities." When he says this, Tadashi can't help thinking about all the time he lost in his world. How long have Hiro and his friends been waiting for him to come back? How long has Cass mourned for him? How long until he can go back…?

What Callaghan says next breaks him out of his morose thoughts: "Then something must have happened to you while you were stuck in that dimension, something that goes beyond Einstein's space-time equations."

"What do you mean?"

"You should be dead, Tadashi." The bluntness of his statement stuns the young man into silence. "Tadashi, the portal is essentially an artificial wormhole, and a wormhole is essentially a three-dimensional tunnel that bypasses space and time. The reason why the portal never worked in the first place was because… well, it's unnatural. It's an artificial construct that was forced to take shape and take in matter that doesn't belong.

"I was there when Krei's scientists built the prototype, and I saw the composition of the space within the wormhole. Organic matter cannot survive long exposure to the properties within that dimension. The electromagnetic plane is filled with negative, cosmic matter, which makes it erratic and the state within unpredictable, and anything extremely dense breaks down into something more insubstantial. It's similar to a black hole; whatever goes in gets pulled apart and it doesn't come back out the same way. At least that's what we thought. When the first portals were made, anything smaller than a baseball cap went in and out the other side unharmed. It was safe to assume anything inorganic could go in, but organic matter was another story. That's when Krei hired a test pilot. My daughter was the unfortunate candidate chosen…" Callaghan's countenance took on a murderous glare. "Needless to say it didn't work. The only reason Abigail survived after being in there so long is because the pod and her suit were designed with a shield that blocked out the electromagnetic forces within the wormhole. Of course, she wouldn't have gotten stuck there in the first place if Krei hadn't—"

"Professor, please stay focused."

Callaghan abashedly coughs into his fist. It seems he's still not over what happened three months ago. "Right, excuse me."

"Didn't Hiro go into the wormhole to save Abigail? He came out pretty much unharmed."

"He wasn't in there as long as Abigail, and because he came out unharmed it's further proof that there are still many things we don't know about wormholes and the spaces between them. Which is why the fact that you not only survived a trip through a wormhole but also traveled from your world to ours without any repercussions is a scientific marvel. To do something so unfounded in such an unstable plane of existence with no protection... Either Sunfire fixed the space-time equation or…" Callaghan pauses.

"Or what?"

He shakes his head, laughing. "The idea itself… it's ridiculous! Unless..."

"Unless what?" The former professor paces within his cell, his eyes tracing invisible equations along the walls of his prison. The suspense is killing Tadashi. He wishes the physics expert would reach whatever conclusion he's coming to faster. Before he realizes it, he's on the glass, his hands grasping for the answers Callaghan refuses to give him. "What are you thinking, professor?"

"Tadashi, you said you don't know how long you were within the portal, right? Or what is was like there?"

"No, I don't. It was… hard to tell time there." The drill of pain that comes with thinking about that place is already giving him a migraine. Colors blot his vision and his stomach churns. He leans against the glass wall, nauseated. "I can't remember anything, professor. It… hurts."

"What about Sunfire? What did you do when he found you?"

This time, remembering hurts less, but his temple continues to throb. "I don't remember the exact details, but… something weird happened when I ran away from Sunfire. He should have been able to catch me…" He mumbles the last part to himself. "One moment I'm in his lab, listening to him drone on about density matrixes and whatnot, then the next I'm… outside…" He pauses. The look on Callaghan's face frightens him. He looks… elated. "Professor?"

"I believe Sunfire is right, Tadashi. _You_ are the solution to the interdimensional travel."

"But… how?!"

"There's a mechanism in quantum theory that's called the 'Everett phone'. Basically, it's a device that allows someone to communicate or even travel traversable wormholes into other universes. It's based on a theoretical nonlinear equation, and I believe that's essentially what happened to you. Your time in the other dimension must have been long enough to allow the electromagnetic energy in that plane to sync with the electromagnetic pulses in your brain, and the cosmic matter spread throughout your body, which converted the negative particles into positive ones, allowing you to travel into this world unharmed. _You_ became the Everett phone."

His head pounds harder and harder as he reevaluates Callaghan's hypothesis. Even though quantum physics is outside his scope of knowledge, he still understands the basics, and the weight of his mentor's words literally sends Tadashi on his knees. "Professor… what are you saying?"

"Tadashi, you may have the power… to freely travel throughout space and time."

Suddenly, it feels like time has stopped and the floor has collapsed from under him. He's no longer in his old professor's cell. Instead, he's in the dilapidated warehouse where he'd run into Sunfire. The villain is wearing the suit, but there is no fire and no mask to hide his identity. But even without the Kabuki mask, his face is still too fuzzy for Tadashi to make out. As he struggles to get clearer look at his abductor, the drill of pain increases tenfold. Slowly, Sunfire approaches him and reaches out, and before he knows it he's outside the warehouse. But he doesn't stop to marvel at this miracle and instead picks himself up and runs out to the street, straight into a blue sonata.

The last thing he hears before the peaceful oblivion of nothingness pulls him under is Callaghan urgently calling for the guards.

* * *

**A/N: Please don't call me out on the science behind this chapter. I majored in zoology, not astrophysics. I did a lot of research about interdimensional travel while writing this story and I still don't understand most of it. Everything I wrote in this chapter is based on what I do understand, for the most part, and there will be chapters just like it that involve other fields of science that I also have a hard time comprehending. But I will admit I did have fun reading about it, and it made writing this story a fun challenge. Science is awesome :)**

**I hope you all enjoyed it!**


	15. Chapter 14: From weird to weirder

**Big Hero 6: ****The Crossover**

**Chapter 14: From weird to weirder**

The drive back to the mansion is spent in an uncomfortable silence thick with tension. Every other minute, Aya's gaze flits from the road to the brooding teen in the passenger's seat and back. He hasn't said a word since they got in the car. His face is still pouty, and his arms are crossed and practically glued to his chest. BaoBao lies in the back, his head between his paws. Looking in the rearview mirror, she sees his ears are deflated, and he looks just as uncomfortable as her.

Hiro still hasn't told her what that phone call was about, and she knows no amount of prying is going to get her an answer. But the silence is much like the foreboding brew of a malevolent storm, and she's not sure she wants to be anywhere near it when it comes. This must have something to do with Tadashi. Hiro is emotionally unstable when it comes to his older brother, and she can only imagine what he and the others did to get Hiro so riled up that he had a meltdown in the middle of a hospital.

As soon as Aya parks the car, Hiro marches inside. She takes her time to let BaoBao out, not too eager to follow the teen. BaoBao whines, and she scratches the back of his ear placatingly. "Don't worry. He's a teen; he's just going through some mood swings."

"Mood swings" doesn't even begin to describe the tantrum that meets her ears.

"What were you guys thinking bringing him to see… _him!_"

"Hiro, calm down—"

"I'm gone for, like, ten minutes and you guys pull this—"

"Hey! You don't get to lecture us!"

BaoBao whines some more and lies prostate in front of the door, covering his head with his paws. Aya leaves him there and heads towards Fred's room where the arguing is taking place. Peeking inside, she sees the rest of BH6 facing the irate teen. Honey Lemon, Wasabi, and Fred look nervous, but GoGo meets their leader's glare with an equally fierce one of her own. Tadashi is nowhere in sight. Honey Lemon meets her eyes and gestures ever so slightly with her head to her left, Aya's right. The nurse nods in understanding and leaves so they can work this out. Meanwhile, she makes it her mission to find the missing Hamada brother.

Whistling for BaoBao to follow, they quickly pass the room and enter the foyer, where they find Baymax. "Baymax, where's Tadashi?"

The giant marshmallow points a finger to the right of the staircase. "He is currently resting. His neurotransmitter levels tell me that he is distraught."

"Thanks. I'll see what I can do to fix that."

"Hiro, GoGo, Honey Lemon, Wasabi, and Fred seem upset as well."

"One thing at a time, big guy." She pats his arm good-naturedly before heading further into the bowels of the mansion, her canine medical assistant right on her heels.

Aya has no idea where she's going. She has only been to the bathroom and the guestrooms, but she still hasn't memorized the layout of the mansion at all so finding his room is pointless. And as helpful as Baymax thought he was being, his instructions weren't very descriptive. So through trial-and-error, she checks every passing room in the hopes of finding Tadashi. Suddenly, BaoBao's ears perk up, and the Jindo jets down the hall. She takes off after him, praying that the dog isn't just leading her on some kind of goose chase. They pass several more doors, one of which she hears the echo of a bowling ball hitting some pins. (There is such a thing as _too_ rich, right?) BaoBao finally stops in front of some double doors, barking eagerly. Tadashi must be on the other side—that or bacon; she wouldn't put it past Fred's folks to have more than one kitchen somewhere in this fancy chateau.

Aya peeks inside and sure enough the older Hamada brother's there, but instead of finding a kitchen or a bedroom, she sees him sitting in the middle of what looks like a basketball court, his arms encircling his knees and hiding his face. Baymax said that he was resting, but he must have woken up some time ago and wandered in here.

Squeezing past his owner, BaoBao trots over to his side, trying to poke his nose through his arms. Aya joins them, sitting herself in front of the stagnant young man.

He lets go of his knees and puts his arms around BaoBao, practically cradling him and shoving his face into his tan and black hide. He mumbles something into the Jindo's neck, but the fur muffles it. BaoBao, who normally hates being held, just cuddles closer to Tadashi, and Aya can't help glaring at the pair of them. Even though he's been trained to comfort people, it still feels like a kick to crotch seeing BaoBao let someone hold him, despite his immense aversion to claustrophobic cuddling. But her hurt feelings are put away when she sees Tadashi's shaking shoulders. "Tadashi…?"

When he pulls away, she's surprised to see two streams of tears running down his face. Aya's heartstrings are being pulled to the limit, and once again she finds herself holding one of the Hamada brothers. BaoBao fidgets and eventually escapes the group hug (and Aya tries not to take it personally), leaving the two young adults hugging in the middle of the basketball court.

Several minutes pass before Tadashi finally calms down. "Don't you dare apologize," Aya forewarns. "I've heard enough of those to last a lifetime." He hiccups, and it sounds suspiciously like a laugh.

When they pull away, Tadashi wipes his remaining tears away with his borrowed SFIT hoodie. "How's Aunt Cass?"

"She's good. She's still wondering where you are, so we told her the truth—about the clinic and staying with Fred, not the interdimensional stuff," she amends when she sees the horrified look on his face. "We didn't get to talk for long. Your brother lost his mind at the hospital and now he's arguing with your friends. I didn't stick around to find out what about, but I have a feeling that it has something to do with you." Tadashi's cheeks burn bright red. "Talk to me."

And so Tadashi recounts his visit to the San Fransokyo Correctional Facility and his conversation with robotics expert Robert Callaghan. As he explains the quantum mechanics of traversable wormholes and interdimensional travel, Aya is completely captivated. For someone to be exposed inside the dimension of a wormhole and sync their brainwaves with cosmic, electromagnetic energy—it's not just science fiction anymore, and she's geeking out from the inside. But when he gets to the part when he passed out in his professor's jail cell, his voice wavering and tone frightened, she reminds her that this isn't just about scientific discovery. This is Tadashi's life. It's new and different, but it's also scary and fickle at the moment; the last thing he needs is someone to analyze him like a high school frog cadaver.

"And now I'm scared out of my mind because… I mean, what do you do when someone tells you that you can freely travel throughout space and time?! This isn't a power anyone should possess, let alone someone like Sunfire! And that's why he wants me. Without me, that portal is just a doorway to nowhere, but once he has me, he'll have access to infinite worlds in infinite timelines whenever he wants—and you're surprisingly calm about all of this."

Aya shrugs. "After finding out that your teenage brother is a superhero, nothing surprises me anymore. But you're not calm about this, and who can blame you? First you get sucked into a wormhole; then you land in this unfamiliar world without your memories; and then when you get your memories back, you find out you're in a parallel universe; and now your former professor, who is a parallel version of the professor who built the portal that sent you here, drops this bombshell on you while you're being chased by some pyromaniac who is also an expert in quantum physics, engineering, and subterfuge. Your life kinda sucks right now."

Tadashi glowers at her halfheartedly. "Thanks."

"So why did you come here? Have you just been freaking out for the past hour by yourself?"

"Yes. Well, kinda. I wasn't sure how to explain to my friends what he told me. Like me being from an alternate world wasn't crazy enough, but now I have this hanging over my head. So I came in here to sort out my thoughts alone. That's when I started freaking out. And then I… tried opening a portal. You know, to see if I really could…" His ears turn as red as his enflamed cheeks, and he avoids eye contact, embarrassed.

Aya thinks it's adorable, like a little kid trying to see if they can fly like a superhero. "Did it work?"

His head falls in disappointment. "No. I haven't been able to do it since I first escaped Sunfire. I've been trying for several minutes, but to no avail. Whenever I try, my head hurts and I feel sick." He rubs his temple as if there's some residual pain there. "I figured if I could control it, then I could face Sunfire alone and finally end this whole thing. My friends would be safe, Hiro and Aunt Cass would be safe…"

"But what about you?"

"What about me? I'm not from here."

"Yeah, but you're just as important as everyone else."

Tadashi heaves a long-suffering sigh. "It's not like it matters. I can't get these powers to work, and even if I did, I don't think I should use them, even against Sunfire. Hiro and the others will find another way to stop him, so none of this matters."

Aya hides a smile. This guy has such a bottomless heart it's hard to believe someone like him exists in any universe. "I can't say I blame you. But honestly, I'd rather be you right now. If I had the ability to escape all my problems, I wouldn't hesitate to use it."

"… How exactly would you do that?" he asks earnestly.

She folds her arms over her knees, suddenly feeling vulnerable. Tadashi's giving her those eyes again; those damn inquisitive eyes that can practically see into her soul. He's snooping again, most likely to forget about his own problems for the time being, but the look in his eyes is nevertheless sincere. Well, she already told one Hamada brother about her issues; what's the harm of telling the other?

"Well, for one I'd go back and apply for scholarships so I could continue to go to SFMI so I could become a doctor and pay for my mother's medical bills. That way after I graduate, I could intern at San Fran Gen, move into a less crappy neighborhood, and apply for grants to do research and… help my mom get better."

"… Oh."

Aya rolls her eyes at the pathetic response. "You and Hiro really are related. And if you dare say sorry about my mom, I will _end_ you."

"I wasn't going to apologize." This stuns her, and it must be showing on her face because Tadashi laughs out loud this time. "I've received a fair share of apologies when I lost my parents. I would never demean someone's loss like that; it only makes them feel worse."

Suddenly, Aya feels a tickle in her throat and a prick in her eyes, and she almost loses it when she sees that stupid, compassionate grin on his face. She looks away from Tadashi as she composes herself. "S-So you know what I mean."

"Yeah, I do."

"And that's why you have superpowers and I don't. The fact that you don't even want to use these abilities means you probably deserve them the most. You wouldn't abuse this gift. So you shouldn't fear them, and you definitely shouldn't deal with them alone. Let your friends help you figure it out."

"I wouldn't necessarily call this a gift."

Aya rolls her eyes again. These boys are making her corneas sore. "You know what I mean, genius."

"I don't even know how to go about telling them about this. They barely believed me when I told them I'm from a parallel world."

"Tadashi, they're your friends. You could turn into a giant five-eyed dragon with butterfly wings and they wouldn't think any differently of you. And Hiro loves you just as much as his other brother."

Tadashi's cheek redden once more. "Yeah, I'm lucky to have them, and you. Thanks for making me feel better, Aya."

This time, Aya feels a flare in her cheeks. She turns away from him once more, but it's hopeless; Tadashi has already seen it. "J-Just doing my job."

"If that were true, you would have just left me here so my friends could take care of me. You also wouldn't have missed another day of work to drive my brother to the hospital to visit our aunt or be sitting here listening to my problems." He's giving her that smirk again; that damn knowing smirk that makes her want to slap it right off his face. "Why can't you just admit you like us, too? Say it." He pokes her.

"No."

Poke. "Say it."

"Tadashi, I swear—"

Poke. "Say it and I'll stop."

Poke. Poke. "Knock it off!"

She shoves him to get her point across, but instead of falling over onto the floor, Tadashi tips into a hole. A hole that wasn't there a second ago.

"Tadashi!" She reaches out and grabs his hand, only to be pulled into the hole with him.

Before she knows it, she's on top of Tadashi in Fred's room, Hiro and the others gawking at them in disbelief.

"Um… what just happened?"

**O—O**

"What were you guys thinking bringing him to see… _him!_"

"Hiro, calm down—"

Hiro doesn't listen. He's so angry he can barely see straight. "I'm gone for, like, ten minutes and you guys pull this—"

"Hey! You don't get to lecture us!" GoGo snaps. None of the others are brave enough to intervene, so they wait out the storm, watching apprehensively as their friends throw jabs back and forth at each other.

It turns out Callaghan was the straw that finally broke the camel's back. Hiro will admit doesn't hate him, but he will definitely never forgive him for what he'd done. So when Honey Lemon called and told him that GoGo and Wasabi took Tadashi to visit the former professor, the teen snapped. Hiro held in everything he wanted to say since leaving the hospital, and he didn't say a word to Aya because he knew he'd blow up as soon as he opened his mouth. Now that he has, he's just getting started.

But that doesn't mean the passive magnetism expert is going to take it lying down. "Just because you never want to see Callaghan doesn't mean we don't. He was the only one who could help us; it only made sense to take Tadashi to see him."

"He doesn't _deserve_ to see Tadashi, not after what he did—!"

"You can't keep blaming him for that. He didn't know."

"He could have saved him!"

"Hiro—"

"I just got him back—!"

"He's not your brother, Hiro!"

"You don't need to tell me that!"

"Then stop acting like you're the only one who lost him!"

GoGo's backlash is like a slap to the face. Honey Lemon looks away, biting her lip and fiddling with her hair. Wasabi looks like he wants to disappear. Fred, who had hidden himself behind the couch sometime during his and GoGo's quarrel, peeks over and frowns sorrowfully. GoGo herself is… crying. It's the first time he's seen her so vulnerable. The sight is bittersweet.

Suddenly Hiro remembers the conversation he had with Aya not so long ago. He had been so consumed with rage when Honey Lemon told them about Tadashi's visit to the prison it was like he had completely forgotten about the very personal things that he told the nurse. He has been so emotionally unstable because of Tadashi. With the inevitability of his departure, Hiro kept his feelings in check, but it obviously isn't working anymore. It's bad enough that he's lying to Aunt Cass, but now he's blowing up at his friends.

Who are obviously suffering just as much as he is.

Hiro sighs tiredly. He can already hear Aya saying, "I told you so."

"I'm so sorry, guys."

"It's okay, Hiro," says Honey Lemon.

"No, it's not. I haven't been myself these past two days. There's been so much going on, but I can't use it as an excuse to play the victim. Tadashi was my brother, but he was also your friend. He was—_is_ just as important to you guys. The Tadashi that came into our lives… he's not our Tadashi; he can't stay here in our world, as much as I wish he would. I've been dealing with it poorly, but I didn't even consider how you guys feel about it."

"Dude, don't even sweat it," says Wasabi. "We understand."

"Yeah, Hiro. I mean, it's like you said, he's your _brother_," says Fred. "If I were you, and my brother died, then came back, and now has to leave because he's from a parallel universe… well, that'd be awesome—"

"What Fred means to say," Honey Lemon butts in before the comic book fanatic can go on a tangent, "is that we forgive you."

Hiro smiles gratefully at the three of them before turning to GoGo, whose back is now facing the whole group. "GoGo, I'm sorry about the things I said to you. It was uncalled for."

She pops her gum, glaring at him. "… It's not okay." Almost like an afterthought, she punches his arm really hard. "But I forgive you, too."

Hiro rubs his arm but doesn't complain. He deserves it, after all. "So what did Tadashi find out from Callaghan?"

Everyone exchanges a uniform glance that makes him feel uneasy. "Well, that's what I was calling about," murmurs Honey Lemon sheepishly. "He sort of… passed out at the prison."

"What?!"

"He's okay," Wasabi quickly reassures him. "He was asleep last time we checked on him."

"We don't know what happened," says GoGo. "But we think Callaghan must have told him something… overwhelming. We thought it was best you talk to him before we talk business."

Hiro takes a few calming breathes before speaking again. "Okay. So where is he?"

Before anyone can answer, two bodies fall out of the ceiling.

It's Tadashi and Aya.

Speechlessly, Hiro looks from the flabbergasted young adults to the hole from which they fell and back again. There are no words to describe this new turn of events.

"Um… what just happened?"

Well, except maybe that.

After a few seconds of bafflement, Tadashi grins awkwardly at his friends and elicits an awkward laugh. "Yeah… there's something I need to tell you guys."


	16. Chapter 15: Comic book soap operas

**Big Hero 6: ****The Crossover**

**Chapter 15: Comic book soap operas**

"Let me get this straight: Callaghan told you the reason that Sunfire needs you is so he can use your 'powers'—powers you allegedly obtained while stuck in the other dimension for who-knows-how long—so he can travel through infinite worlds in infinite timelines whenever he wants. Which is how you and Aya fell out of the ceiling."

"… Yeah, basically."

GoGo looks at the rest of Big Hero 6, who exchange dubious glances. This doesn't make Tadashi feel any better about what Aya said. Maybe they would prefer a five-eyed dragon with butterfly wings over this.

After explaining what Callaghan told him at the prison, the others responded just as well as they had when he told them about his interdimensional origins. It took a few more minutes to answer their bounty of questions, and after a lengthy discourse about the general theory of relativity, quantum physics, and Einstein spacetime equations, it seems they finally understand (except for Fred, who, for a majority of the Q&A, was staring at the hole from which he and Aya fell).

He wishes Aya hadn't left him to deal with this alone. She had understood almost immediately, and he's sure her input would have made this discussion a little more comprehensive. But after their startling fall, she had wordlessly left the room. It seems she overestimated her capacity to adapt to these outlandish changes of development in this spiraling chronicle that is now her life. She most likely went to find BaoBao before he freaked out, if he isn't already. It's taking her a while to get back, but he wouldn't be surprised if she intentionally got herself lost in the labyrinthine mansion just to take a break from all this… he doesn't even know what to call it anymore.

"Well, this does explain the anomaly Baymax told me about when he scanned you," Hiro finally says. Out of all the members of BH6, he seems the least surprised by this new development.

"Wait, when did you scan him?" asks Honey Lemon. Not for the first time, she looks like an elementary school teacher scolding a student for cheating on a test. It's an effective look because Hiro suddenly gains a conciliatory smile and self-conscious disposition.

"I thought he might have damaged his brain during the fire?"

GoGo rolls her eyes. "You're an idiot."

"What exactly did the scans show you?" asks Tadashi. Hiro had mentioned before that there was something weird about his bioscan, but he never said to what extent. Re-analyzing the results could be the clue to controlling his powers; it would be nice not to have to worry about falling through any more spontaneous voids in space.

"According to Baymax, there was some sort of substance in your nervous system. He couldn't identify it."

"Is there any way you can bring up the scans?"

"Yeah, but I need Baymax." As if on cue, the healthcare robot appears at the door, along with the black and tan Korean Jindo without his owner. "Baymax, I need to borrow the healthcare chip for a sec." The giant marshmallow complies, allowing the teen to eject the chip.

As Hiro uploads the data onto his laptop, Tadashi beckons BaoBao to join him on the couch. He obediently jumps up and rests his head on his lap, whining in pleasure as the young man scratches his ears. Honey Lemon joins them and starts rubbing the dog's belly, and soon BaoBao is buried in an overabundance of affection from the other members of BH6. Even Baymax waddles over to pet the compliant Jindo. "Hairy baby…"

"Found it!" Hiro cries out in victory.

Fred's wall opens up once again to reveal a screen showing a diagram. On the right side of each diagram is a chart full of random medical jargon explaining the condition of the patient. Tadashi's eyes widen as he scrutinizes the left side. A gray silhouette of the human form ripples with pulsing electric blue lines running through its entire anatomy. The nerves intersecting the human silhouette look normal up until he reaches the cranium, which is pulsing violently with scarlet energy. When combined with the electric blue pulses, the neural pathways pop in a violet haze that makes the image look ominous. The scarlet energy gradually spreads to the other nerves, slinking down the silhouette's body like a venomous serpent before receding back to the head, and the pattern repeats. It's fascinating, but in a way that makes his insides squirm. Even though Callaghan explained it to him, the diagram makes the reality of his abilities more concrete.

"What is that?" susurrates Honey Lemon. She and the others share the same look of alarm.

"Baymax didn't recognize it when he first scanned Tadashi, but I think I have an idea of what that is. If what Callaghan said was true, then the cosmic matter inside the portal must have fused with his electromagnetic signature, resulting in… well, that." He points up at the portal in the ceiling. It looks smaller, but the basketball court is still in sight.

"How long is that going to be here?" asks GoGo.

"Better question," interjects Fred, "can you make another one that goes to the kitchen?" This earns him a slap to the back of the head.

"I don't know how to control it," Tadashi replies. "I've only been able to open a portal twice. Every time I try, I feel sick." The sickening drill returns just as he says this, and it pounds behind his temples unremittingly.

"That's because you're forcing it," says Hiro. Despite the unease etched into his features, he remains staid as he mulls over Tadashi's predicament. "The cosmic energy is concentrated in your cerebral cortex, which is probably why it hurts whenever you try to activate your powers. You're thinking too hard."

"Are you suggesting I stop thinking?"

The teen shrugs. "It could work."

"I don't think thinking is the problem," inputs Honey Lemon. "Maybe your powers have something to do with the chemistry in your brain. The first time you used them, you were trying to escape a villain. The fear must have triggered your abilities."

"But I wasn't afraid the second time I did it. I was actually thinking about you guys." Tadashi's ears turn pink as Honey Lemon gushes.

"So we're back to square one," deadpans GoGo.

"We should do more research," Wasabi proposes. "Clearly none of us know anything about the brain."

"Yeah! SCIENCE!"

As the others continue to brainstorm, Tadashi exchanges a look with BaoBao. "You wouldn't happen to have any ideas, would you?" BaoBao jumps off the couch and runs out the door, most likely in search of his owner. A fresh perspective would be helpful. He's not sure how much Aya knows about quantum physics, but he does know that every science major has to take at least a year of general physics and Aya certainly didn't look bored when he told her about Callaghan's hypothesis. She could help them. If only he knew where she went…

"Thanks, Heathcliff." He watches the young woman as she sips from a mug that smells like cinnamon and decaf. "I really needed this."

Wait a minute. How is he watching this?

"You're welcome, miss."

"You've obviously been helping Fred and his friends for a while. How do you deal with all this without going completely insane?"

"I've been the butler for this family for over fifty. Nothing surprises me anymore."

"Dudes! The other portal's gone!"

Fred's outcry alerts the two in the kitchen. Heathcliff looks nonplussed. "Good evening, Master Tadashi."

Aya, on the other hand, nearly falls out of her chair in astonishment. "Again! _Seriously?!_"

The other voices draw the superheroes back to the couch where Tadashi is still trying to figure out how he summoned this portal. "Whoa, Tadashi, how'd you do this?" inquires Wasabi.

"I don't know…"

"Is there any way you can _undo_ it?" huffs Aya indignantly. "I swear, you people are going to give me gray hairs."

Meanwhile, Fred jumps into the kitchen and back into his room and so on and so forth. BaoBao, who was sitting quietly under Aya's chair, joins him, enjoying this fun, new game. "This is awesome! Dude, now open a portal into the garden!"

"I still don't know how it works!"

"… Try making a portal in Cass's hospital room."

Tadashi stares at his little brother in exasperation. "Didn't you just hear me? I. Don't. Know. How!"

"Just try." It takes all of Tadashi's willpower not to shake some sense into him. But as he glares heatedly at his younger brother, Tadashi sees that familiar glint, that natural curiosity that strove forth brilliant ideas and momentous revelations about the world. Hiro might have figured out how his powers work.

Breaking away from their stare-off, Tadashi goes along with Hiro's plan and concentrates as he tries to summon another portal. His headache comes back tenfold, drilling and hammering into his brain. He closes his eyes and cries out in pain, clutching his head as the piercing agony increases by the second.

"Tadashi!" A dainty hand grasps his shoulder. "Stop!"

When he opens his eyes again, he still sees Heathcliff and Aya, their expressions full of worry and slight panic. Honey Lemon grasps his arm as he slumps forward. "I-I'm okay…"

"Now try the café."

"Hiro, it didn't work," says Aya.

"He can do this."

"But it's obviously causing him pain," says Honey Lemon. "He can try again later."

"N-No, I can do this." Tadashi waits a moment for the nausea to dispel and tries again. But instead of concentrating solely on the café, he thinks of the times he spent there, studying with his friends, cooking with Aunt Cass, inventing new things with Hiro. He thinks of all the memories he's gained since his parents' deaths, the good, the bad, the ugly—everything that made the Lucky Cat Café feel like home.

In a blink of an eye, another portal appears, this time showing the charred image of the Lucky Cat Café. The other portal closes just as quickly, and Fred is pulled to safety while BaoBao disappears in the kitchen with Aya and Heathcliff. "Whoa! What just happened?"

"You nearly got chopped in half by a two-dimensional void!" Wasabi shrieks.

"No more playing in portals," GoGo warns.

The mental exertion of summoning the portal physically fatigues him. Honey's steady grip keeps him from falling off the couch. "Tadashi!"

GoGo punches their young leader in the arm. "Hiro, what the hell were you thinking?"

"Hey, it worked, didn't it? I knew he could do it."

"And look at what it did to him."

Hiro meets his gaze, and suddenly his haughty countenance converts into remorse. "Don't give me that look, Hiro. If I hadn't pushed myself going along with your plan, I never would have been able to figure out how to use my powers. And now we know how it works… sort of."

"And you nearly killed yourself in the process," GoGo reminds him.

"But it _worked_," the brothers reiterate pigheadedly.

She rolls her eyes. "You're both idiots. Aya's going to have a field day with you both."

Not a moment too soon, the nurse busts into the room, BaoBao on her heels. She plants herself in front of the Hamada brothers, handing the older one a water bottle. "Are you okay?"

He takes in several gulps of water before handing it back. "Yeah, thanks."

"Good." With a flick of the wrist, she bops both brothers on the head with the water bottle. The cheap plastic doesn't even hurt, but the action itself makes both of them flinch. "You're both _idiots!_"

"Hey, if we didn't test his powers out—"

"I don't want to hear it! What you did was totally reckless!"

"But it _worked!_"

Aya pinches the bridge of her nose in exasperation. "You two are impossible." She leaves, muttering something about gray hairs and troublesome teens.

"Aya, wait!" Despite his migraine, Tadashi quickly catches her in the hall. "I'm sorry for making you worry. I just…"

To his utter disbelief, Aya pulls him into a crushing hug. He holds his arms up awkwardly. Aya has never given him any form of affection, at least not physically. He doesn't want to spook her by returning the embrace. A solid minute passes since she first initiated the hug and she still hasn't moved. He chances it and fully embraces her, relishing the feel of her in his arms. He holds her hand firmly even after she pulls away. Her face is completely flushed. "Never speak of this."

He smiles impishly. He's never going to let her live this down. "Of course." He squeezes her hand one last time before releasing her. Once she and BaoBao disappear around the corner, he returns to Fred's room and is met by the deceptively innocuous faces of his friends. "What?"

They all exchange coy glances. "Nothing," teases Wasabi. When he sees Fred making kissy faces, Tadashi blushes.

GoGo shoves Fred's face, stopping his antics. "So now what?"

Before anyone can answer, Hiro's phone goes off. "It's Krei." Tadashi and the others exchange a look. "What?"

"It's recently come to our attention," says Wasabi, "that Krei may have been working with Sunfire this whole time."

"What?!"

"We'll explain later," says GoGo. "Just answer."

Hiro does so, putting the caller on speaker so everyone can hear. "What is it, Krei?"

"_Hiro! I'm so glad you answered! Can you and your team come to my office, as Big Hero 6? There's something I need to tell you all. It's important._"

Tadashi doesn't even need to look at the others to know what they're thinking: this is so obviously a trap. "Why can't you tell us now?"

"_Because Sunfire could be listening and I don't want to get in trouble with him again!_"

"What do you mean 'again'?"

"… _Okay! I admit it! I lied about Sunfire taking the portal. But he threatened to kill me if I didn't cooperate! Now I really need you guys to get over here! Sunfire came back and I need you to get rid of him!_"

"He's there, seriously?"

"_Yes! He wanted to get something from the lab, so I gave him access. He'll be back any minute, so please hurry!_" The call ends before Hiro can reply.

"I think that's the first time Krei has ever said please," Honey Lemon muses.

"Should we still go?" asks Wasabi. "I mean, this is clearly a trap."

"You guys should go," says Tadashi. The others still look a little uncertain, and he can understand why. Now that they're aware of Sunfire's plans for him, the possibility of Krei's cry for help being a trap raises even more red flags. "Look, even if it is a trap, at least you'll have a chance to catch Sunfire. And it's not like he knows where I am. The sooner this is over, the better."

Of course, being the superhero enthusiast he is, Fred speaks out first, putting an arm around Tadashi in camaraderie. "I like it! We'll let the villain think they've trapped us, but we'll be the ones doing the trapping!"

"It's not really a trap if he knows we're coming, Freddie," says Honey Lemon.

"I'm in," says GoGo. She punches her fist into her open palm. "Let's get this maniac."

Exchanging a droll smirk with his brother, the youngest member of Big Hero 6 turns to his friends with a new sense of bravado. "Then it's decided. Let's suit up."

All of a sudden, the back wall of Fred's room opens up. Tadashi stares in awe when a colorful ensemble of what can only be super suits emerge. He slowly walks up to the giant red one. This can only belong to one person. He looks back at his little brother in disbelief. "Did you turn my healthcare robot into a crime-fighting machine?"

The teen merely shrugs as he walks up to a dark violet suit that can only fit someone his size. "Consider this a part of his healthcare protocol."

**O—O**

Aya sighs in relief as she parks into the San Fransokyo General Hospital visitors' lot. She's starting to think that skipping work these past two days has been a mistake; dealing with coke heads and hypochondriacs was much simpler than this sci-fi drama she's been living in. Why do nerds want anything to do with this stuff? It's only been three days, but she's worked behind the scenes long enough to know that comic books aren't an accurate interpretation of the real thing. And it's so frickin' _stressful_.

There's not enough coffee in the world to help her deal with this nonsense.

All she wants to do is take a nap on her lumpy couch and watch reruns of soap operas on cable. But no amount of exhaustion could prevent her from visiting her comatose mother. She'll just close her eyes for a little bit before going in…

The buzz of her vibrating cell phone abruptly wakes her up before her head hits the steering wheel. Digging through her purse, she silently curses whoever's on the other end before finally grasping her phone and hissing, "WHAT."

"_Aya, thank God! I've been trying to reach you for two days! Where the hell have you been?!_"

Oh no. She knows that voice. "H-Hey, Nicki! Listen, if this is about the other day at the blood drive, I can explain—"

"_What the hell happened to you?!_"

"… I'm sorry?"

The doctor huffs on the other end. They're clearly not on the same page. "_I called you like fifty times yesterday, but you didn't answer! Your landlord said you hadn't come back since yesterday, and when I went to the clinic they said you were kidnapped by some guy dressed in cosplay! Are you okay?! Where are you?!_"

Oh. That explains it. Now that she thinks about it, this is the first time she's used her phone in over a day. Sure enough, when Aya opens up her voicemail, she sees exactly fifty-five missed calls from "ICE Nicki". "I wasn't kidnapped. I was… recruited, sort of. I'll explain when I get inside."

"_You better, and don't think I've forgotten about the stunt you pulled with that John Doe._"

Aya hangs up, the doctor's threat adding to the immense weight to the accumulating fatigue she's gained these past two days. She feels like crying. All she wants is a nap.

After a few minutes, she finally musters the strength and a little bit of courage to get out of her sonata and enter the hospital; the sooner she faces Nicki's unadulterated temper, the sooner she can return to those soft, silky Egyptian cotton sheets and drift off into dreamland. But she still doesn't have enough courage to face Nicki, so she takes a detour into the ICU. She waves amiably at Kim, who is at her usual station, and makes her way to her mother's room. Even in her vegetative state, her comforting presence always gives her the energy to deal with the trials of her life.

When Aya opens the door, she's surprised to see that someone is already occupying the chair next to her mother's bed. She doesn't recognize this person at all. Other than her mother, she has no family to speak of, and her friends worked at this hospital. So seeing that this stranger isn't a medical professional or a woman immediately flashes a red flag in her frontal lobe.

She doesn't bother beating around the bush. "Who are you, and what are you doing in my mom's room?"

The stranger doesn't move. "I'm… an old friend."

"I don't recognize you."

He slowly stands from his seat and turns, and Aya is met by a shockingly familiar sight. "Are you sure?" His hand hovers over her mother's peaceful form. A flame flickers inches away from her unconscious face. "How about now?"

No, no, no—this _can't_ be happening. Of all the conceivably horrible things she imagined could happen in this room, this is much, much worst. "What do you want?"

"We both know what I want. And you're going to help me get it."

She backs into the door, closing it. BaoBao, who is still on the other side, whines and scratches at the door. "And if I don't?"

"I think you know what will happen." He draws his hand closer, and the flames practically lick her mother's cheek.

"Get away from her!" Without a second thought, Aya lunges towards him, tugging his scorching hand away from her mother. With the fire expelled, the villain grabs her other wrist and twists her arm around her back. She opens her mouth to scream only to be stifled by an odorous rag soaked in chloroform. Oh crap.

"Thank you for making this easier for me."

She struggles against him, or she tries to, anyway. Before she knows it, she's on the floor, her limbs numb and her mind full of cotton. She fights the effects of the drug and tries finding her phone before the remnants of consciousness escape her. Her paralyzed fingers barely brush the screen before she's out cold.


	17. Chapter 16: Time to suit up!

**Big Hero 6: ****The Crossover**

**Chapter 16: Time to suit up!**

As Big Hero 6 makes their way to Krei Tech building, the others fill Hiro in on their recent discovery. Afterwards, the urgency to reach Krei's office practically becomes nonexistent. With the portal's apparatus in his possession, it was only a matter of time before Krei decided to restart Project: Silent Sparrow (a ridiculous name, in Hiro's opinion). The business tycoon was already untrustworthy without the prospect of his alleged allegiance with this new supervillain. This distress call is most certainly a trap.

Sunfire's fascination with Tadashi also makes a lot more sense now; he was aware of Tadashi's abilities from the beginning. And if he truly is from a parallel universe, those abilities may be of use to him. But something still feels off to Hiro. If all this guy wanted to do was to go back home, then he could have asked for help; he didn't have to steal the portal. Also, since he has the portal, what the hell does he need Tadashi for? No, he must have something else planned, something dangerous, and the fact that he's been evading the heroes makes it hard to believe that he's been up to any good. As far as Hiro is concerned, it's too late to even consider him as anything other than an enemy, not after what happened with Callaghan; it just hit too close to home.

Everyone jumps off of Baymax as soon as they're in Krei's office. It's expectedly empty. The only thing to greet the team is an image of Sunfire's masked face on Krei's laptop screen.

"It's a video." The short hero immediately takes a seat behind the desk.

Before he can play the video, a blue claw nearly hits him in the face as it blocks his view of the screen. "Wait! This could be another trap!"

"Once again, I'm going to regret saying this, but Fred may be right." GoGo looks as if saying so leaves a foul taste in her mouth. "Today has been extremely weird."

But Hiro doesn't care about the risks. So far, dealing with Sunfire has been like playing the most complicated game of cat and mouse. Tracking and fighting Yokai had been much easier than this; it only took a day to deal with him. They've been at this for three days with no success, and now they have a chance to get some answers. "We came here knowing it was a trap. Might as well see what he has to say." Without further ado, Hiro plays the pre-recorded message.

"_Greetings, heroes._" From the deep, warbled audio, Sunfire's voice has been altered beyond recognition. Hiro's never heard him talk, but the menacing bass that has supposedly replaced his original vocals suits him."_I'm sure by now you've figured out that this a trap. Well, not a trap per se. If I truly wanted to entrap you, I would have used much more effective means than Krei. He's a bit of a dolt, but he's been very helpful. He'll bow down to anyone who threatens to single hair on his greasy head. Considering how easily he betrayed you, perhaps you should reconsider working for him_."

"He has a point."

GoGo elbows Wasabi. "It's not like we have much of a choice. Blackmail, remember?"

"_You know what I want, so I'd prefer if we don't waste any more time. Give me Tadashi Hamada. You know just as well as I that he does not belong here, and the sooner he is within my possession, the sooner we _both_ will be out of your hair and back into the worlds to which we belong. I know none of you have any reason to trust me but believe me when I say I am not your enemy. Despite what you may think, I never wanted to cause anyone any harm. I just want to… to make things right. And as a gesture of good will, I have deleted all the files Krei has on Big Hero 6._"

The heroes exchange astonished looks.

"_Choose quickly, heroes. Time is of the essence, and there's no telling how our presence will affect your world._" As soon as the video ends, the screen goes black.

Hiro presses the power button, but it's no use. "It's not working. He must have put planted a virus in the video."

"So… am I the only one considering Sunfire's offer?" This time, GoGo punches Wasabi in the arm with full force. "Ow!"

"We're not turning in Tadashi."

"That's right! We don't negotiate with supervillains! Everyone knows that they never follow through on their promises! That's Superhero 101 stuff!" Fred stands akimbo next to his burly friend, wagging his clawed finger in his face beratingly. "Shame on you, Wasabi."

"But would a villain help protect our identities from the likes of someone like Krei?" Honey Lemon speculates, nervously clutching the strap of her chemical bag. "Besides, he said he doesn't want to hurt anyone. He wants to end this peacefully. Maybe we should consider…"

Hiro stands from the seat angrily. "Consider what? Handing my brother over to the psychopath who burned down my home and nearly killed the only family I have left? If Sunfire really wanted to end things peacefully, he should have contacted us first instead of threatening us."

"Besides, even if we did give him Tadashi, who's to say he'd actually go back to his own world?" GoGo adds. "If he truly discovered a way to travel to other worlds, then handing over Tadashi would be like giving him full reign over the multiverse. He could use Tadashi to do whatever he wants _whenever_ he wants."

Honey Lemon and Wasabi still look skeptical, and Hiro is outraged that they're still considering Sunfire's offer. Finally, Honey Lemon heaves a sigh. "Okay. We won't hand over Tadashi. He may not be our Tadashi, but he's still our friend."

"But I still think Sunfire has a point," says Wasabi. "What if Tadashi and Sunfire being here does have negative consequences in our universe?"

"Sunfire's been here for a week, and Tadashi three days after that. So far, the only negative consequence has been Sunfire going after my brother. I don't even know why we're still talking about this. We're not negotiating with him."

"Hiro, that doesn't change the fact that Tadashi doesn't belong here."

Hiro glares at the laser expert. As resigned as he is to the idea of Tadashi leaving, talking about it still makes him uncomfortable. However, the idea of letting Sunfire anywhere near Tadashi brings about an entirely new kind of dread that makes his stomach twist into incorrigible knots. "Then we'll find a way to get him back to where he belongs. In the meantime, we stick to our original plan: find Sunfire, get the portal back, and then we'll get some real answers out of him. Baymax, scan—"

Before he can finish the edict, an alert beeps from the cuff in his left glove. Hiro opens it to reveal a smaller screen playing live news footage. He curses under his breath, and as the others gather around to see what he's watching, he turns to look at Wasabi and sneers sardonically, "Still think we should take his deal?"

**O—O**

Tadashi stretches his arms over his head and yawns contently. That was one satisfying nap. After his friends left, he thought it was a good idea to rest his eyes for a few minutes. He doesn't know how long he's been out, but according to the digital clock on the desk it's definitely been more than a few minutes. Who knew opening portals through voids in space with your mind could be so mentally and physically exhausting?

As he absentmindedly wanders the hallway, Tadashi thinks about practicing with his powers a little more but immediately rescinds the thought when the lingering migraine from earlier pokes at his temple. At this rate, he may never be able to use these powers, not if they keep causing him pain like this.

Tadashi doesn't plan on becoming a superhero. As much as he wants to help people, the superhero thing isn't as appealing to him as it is to Fred and his other friends. But now that he knows what he's capable of, he'd at least like to get a handle on his newly acquired powers so he doesn't accidentally open random voids in space. Unfortunately, even remotely thinking about it feels like his brain is about to split in half. Until he can find another way to make them work without suffering from chronic migraines, he'll just have to cross his fingers and hope he doesn't wind up falling through the floor again.

In the meantime, Tadashi will wait for his friends to return.

"Pardon me, Master Tadashi."

"AH!" Tadashi jumps at the sudden appearance of Fred's butler. "Heathcliff! You sure are light on your feet, aren't you?"

"My apologies for frightening you, sir. I just came to inform you that you have a guest."

"I do? Who—"

Suddenly, a black and tan blur tackles him, and they both topple hard onto the floor. "BaoBao?" The fidgety canine jumps off of him, running in circles frenetically. "Hey! Easy, boy! Calm down!" Tadashi grabs the dog's vest to keep him still, befuddled by his unruliness. BaoBao is normally so well behaved, at least while Aya is around. Speaking of which, the nurse is nowhere to be seen. "Where's Aya, boy?"

At the mention of his owner, BaoBao prods his nose into the young man's chest. Something's sticking out of his mouth. Suddenly, the object buzzes, prompting the dog to drop it. Tadashi picks up the slobbery cell phone as BaoBao lies down, resting his head between his paws and whimpering. That is not a good sign.

He quickly wipes the sodden phone on his shirt before checking caller ID. The name "ICE Nicki" blinks up at him. That name sounds familiar. With mild hesitance, he answers the call. "Aya…?"

"… _Who is this?_"

The voice sounds familiar, too. An image of a tall brunette in blue scrubs glaring daggers at him and threatening to break his legs suddenly pops into his head. "… Nicki?"

"_Who the hell is this?!_"

Yikes. Even on the phone he can still feel the murderous intent in the doctor's voice. "I'm the concussive John Doe Aya found a few days ago, remember?"

"… _Wait, for real?_"

"Yes...?"

"_So he's still alive_." From her hushed tone, he's sure he wasn't supposed to hear that. His concussion must have been more serious than he thought if she didn't think he'd survive outside the hospital. "_You two have a lot of explaining to do. Now drag Aya out from whatever hole she's hiding or I'll come out there and—_"

"Aya's not with me." A prickle of panic stabs his chest. "Isn't she at the hospital?"

"_Well, I thought she was. I just talked to her an hour ago, and according to her she was in the parking lot._" Her ire quickly transforms into full-fledged panic. "_If Aya's not with you, why do you have her phone? Where is she?_"

The prickle transforms into a painful stab that leaves a raw ache in his chest. "I don't know… but I'm going to find out." After he hangs up, he runs his unsullied hand through his unruly hair in a tizzy.

Aya's missing. She's alone without a cell phone and without BaoBao, and not even her friend knows where she is. He has a feeling he knows what happened to her, but he doesn't want to go there. Not yet.

He turns to the butler, who has been standing off to the side dutifully. "Heathcliff, how long do you think it will be before my friends come back?"

"They actually arrived a few minutes ago, sir. They're in the gardens in the back."

"Perfect. Thank you, Heathcliff." Tadashi makes a mad dash down the hall and quickly returns when he realizes something. "I have no idea where I'm going. Can you take me to them?"

A few minutes later, Tadashi and BaoBao find themselves in the most beautifully landscaped garden the young man has ever seen. It would serve as a magnificent playground for a rambunctious pup like BaoBao—though the owners probably wouldn't appreciate him putting it to use—but the canine stays by Tadashi's side obediently. He must be too worried about his owner to even think about tearing apart those expertly trimmed topiaries. Hiro and the others, still dressed in the superhero regalia, are huddled inside a gazebo in the back. Baymax, mighty and colossal in his crimson glory, stands a little ways away, staring at a butterfly that landed in his massive fist. Even in that intimidating getup, he still looks adorable.

Wasabi is the first to take notice of his approach. Slowly, the group breaks up the huddle, allowing Tadashi to see their colorful array of super suits, from the bright pink and orange Honey Lemon all the way to the blue monster suit containing his comic book savvy friend. "Man, I'm not sure I'm ever going to get used to seeing you guys dressed like this." He stops when he sees the looks on their faces. Their collective solemnness puts him off. "What's going on?"

"Turns out we were right," says Hiro as he closes a compartment in his glove. "Krei set us up so Sunfire could distract us long enough to steal from Yoshida Labs."

"Why would he do that?"

"No idea. We don't know what he took since, according to the head of Research and Development, it's a secret project, but no doubt it can't be for anything good."

The recognizant pop of bubblegum echoes under the canopy of the gazebo. GoGo looks ready to eviscerate someone with her magnetic discs. "We need to find him immediately."

Fred pulls up his hood, sporting a comically analytical visage. "This is a shrewd opponent, indeed. That offer he gave us was just a ploy all along. I told you villains never keep their word."

Hiro shoots him lethal look. "Fred!"

"What's he talking about?"

No one answers immediately. Hiro pulls Fred's monster head back over his head while GoGo crosses her arms and leans against the banister of the gazebo. Wasabi in particular pointedly avoids looking at him. Honey Lemon bites her lip before finally answering. "Sunfire left us a video at Krei's office. He wants us to hand you over."

No wonder none of them can look at him. "I'm guessing you guys are debating whether or not you should actually go through with it."

"No." Hiro parts from the group and steps up to his other-dimensional brother. And he looks extremely pissed. They must have already had this discussion. "We're not giving you to Sunfire. We can't trust him."

"It's okay, Hiro." He puts a hand on Hiro's shoulder, smiling reassuringly at the rest of his friends. "I understand everyone's skepticism. I may be Tadashi Hamada, but let's face facts: I don't belong here, and there's no telling what sort of repercussions my being here may have on your universe." Hiro looks ready to object, but Tadashi quickly interjects before he can. "But we can worry about that later. We have another problem. Aya's missing."

Big Hero 6 gaps at him. "What? How do you know?"

"BaoBao arrived here by himself with her cell phone, and her friend just called Aya's phone from the hospital. Nobody knows where she is, and I doubt she'd just let BaoBao run off with her only means of communicating with us." Hiro has a grim look on his face that chafes the raw ache in his chest. "What are you thinking, little brother?"

"I'm thinking it's pretty obvious who took her."

Tadashi sighs in resignation. Hiro's right. There's only one culprit.

He knows Sunfire was bound to make a move, but he never thought he'd resort to taking someone hostage. Then again, he did try to lure Tadashi by setting the Lucky Cat Café on fire…

It's bad enough Sunfire saw fit to put his family in harm's way, but Aya shouldn't have anything to do with this mess. She isn't a superhero, and as far as he knows she doesn't have superpowers. She's just a bystander who was unlucky enough to get caught in the crossfires of Tadashi's predicament. But that's exactly what the flame-based villain is counting on. He wants Tadashi to find him, to rescue his friend, and probably exchange her life for the use of his abilities in order to do God knows what. As far as Tadashi is concerned, Sunfire is the last person—in this universe and others—who should wield these abilities.

And he will be damned if he lets Sunfire get away with this.

"But how could Sunfire have taken her while he was at Yoshida Labs?" asks Honey Lemon.

"It can't be a coincidence that she just happens to go missing while we were at Krei's office," says Hiro. "Besides, the guy perfected the formula for interdimensional travel; I'm sure he could have found a way to kidnap Aya during his heist. And if she's with him, that means she's also with the portal. We have no choice now. We need to end this today."

"I'm coming with you." Everyone stops and stares at the elder Hamada brother. Hiro looks especially alarmed at his announcement. "Sunfire kidnapped Aya because of me. I have to go."

"Which is exactly why you shouldn't," says GoGo. "This is obviously another trap."

"I know, but what other choice do we have?"

Fred pulls the head of his suit back up. "Easy. We just go to his secret lair and kick his butt."

"But fighting him is futile. He's been able to evade your notice for a week, and if I'm not there, there's no telling what he'll do to you guys. If things get hairy, I can at least summon a portal—"

"Tadashi, you can't even use your powers without getting a headache," Hiro sharply retorts. "And just because you have superpowers doesn't mean you're suddenly an expert."

"And being the leader of a superhero team doesn't make you my boss, _Hiro_." The brothers stare at each other, unyielding. Tadashi understands Hiro's concern, but this isn't something he can just step back and watch from a distance. Aya is in danger, and he's her only salvation. "Look, I may not be your Tadashi, but I'm still your older brother. And if you expect me to stay behind while my little brother and my best friends fight my battles for me the, well, I guess you never really knew Tadashi at all."

The biting words taste bitter on his tongue, but it needed to be said. The effect it has on Hiro is instantaneous, and suddenly Tadashi is reminded of the fight he had with his real little brother. The hurt in his eyes mirrors that of his Hiro, making his insides squirm fitfully, but he stands his ground. The others stare wide-eyed and tongue-tied; they've probably never seen Tadashi fight with Hiro. BaoBao whimpers in the background as if he can sense the rising tension between the contending brothers.

Finally, Hiro closes his eyes and takes a deep, even breath. When he opens them again, Tadashi is surprised to see tears accompanied by a watery smile. "You're just as ridiculously stubborn as him."

Tadashi smirks and ruffles his hair. "I wouldn't be Tadashi if I wasn't."

"Welcome to the team, dude!" Fred puts his rubbery, blue arm around the older Hamada brother. "Oh! You're going to need a costume! But first, let's talk names—!"

"No." GoGo pulls him away, much to Tadashi's relief. Fred's suit is shockingly heavy.

"But Fred's right," says the younger Hamada brother. "Sort of. You can't rely on your powers to help you during a fight. When things go south, you need a way of protecting yourself. We need to suit you up."

"How are you going to build me a suit within the next few hours?"

The team exchanges a uniform look of mischief. "Time to take a little trip to the university."

**O—O**

When Tadashi enters the robotics lab at the San Fransokyo Institute of Technology, he is filled with mixed feelings. The lab is the place that started it all: it was where he first met Professor Callaghan and Abigail; it was the place that sparked his imagination and helped him create many inventions that helped countless others; it was the birthplace of his proudest achievement, Baymax. But there had been just as many tears shed here as there were moments of nostalgic joy.

The first few weeks of his fifth semester were some of the most challenging throughout his college career. This was around the time he finally started talking more classes related to the robotics program and when he first acquired the lab. Tadashi was ready to unleash his imagination on the fresh, new, bleached whiteboard, and he couldn't wait to showcase his ideas to his professors, especially the renowned Robert Callaghan. But as soon as he sat at his desk, the college junior was at a blank. His head was full of many ideas, but most of those projects ended up in the bin. It frustrated him how none of this came as easily to him as it did for his genius younger brother, but he refused to give up. He may not be a prodigy, but he could still make the world a better place once he put his mind to it.

But this lab doesn't bring about the same aspiring ambiance it had evoked from the students that entered its walls. In fact, the place looks a little downtrodden. Tadashi can't tell if it's because of the lack of students or the missing pictures and plaques of Professor Callaghan and his many accolades, but something doesn't feel right.

"Where is everybody?"

"They started the new renovations today," Hiro surmises. "Since they started adding new building, the school decided to fix up some of the older ones too."

"Oh! And you'll love this." Honey Lemon practically bounces in her six-inch heels in glee (how she can do that without breaking her ankles, Tadashi can only wonder). "They named one of the buildings after you!"

Tadashi stops in his tracks. "What? Really?"

"Well, after the other you, but yeah. After the other you, you know, the school thought it would be a nice way to commemorate one of their brightest students." Hiro grins at the incredulous look on his brother's face. "You were a really popular guy. A lot of people looked up to you." Tadashi's heart is filled with an overflowing bounty of adoration for his fellow classmates and teachers. He had no idea people thought so highly of him, and he wonders if the notion is emulated in his own world. Either way, it's humbling to know that the other Tadashi had such an impact on the school.

"I… have no words. It's—" He coughs, wiping a stray tear from his eye "—it's not every day you hear that your alternate self gets a building named after them." Baymax offers him a tissue, but he politely declines it.

"Maybe they've named a building after you in your world," says Honey encouragingly.

"I should be so lucky."

"Dude, you're _Tadashi_. Your world would be _dumb_ not to name something after you."

"I'm with Fred," Wasabi concurs. "If anyone deserves to have something named after them, it's you."

Honey Lemon puts a hand on his shoulder. "You should give yourself more credit, Tadashi." Everyone offers him a heartening grin, except for GoGo, who pops her gum.

Tadashi's cheeks warm up. "Of course you guys would say that…"

GoGo punches his arm. "Woman up." To Hiro she says, "Get to work."

From there, everyone diverges to their own stations, except for Fred, who chills on the couch next to Honey Lemon's station. Tadashi, Hiro, and Baymax make their way to Tadashi's lab. Well, Tadashi supposes he shouldn't call it that anymore.

"Hope you don't mind that I took over your lab," the younger Hamada jokes as he unlocks the door. "Sorry, it's kind of a mess."

Tadashi takes a moment to glance around the room. The late afternoon sun shines through the circular window, lighting up the whiteboard, which is dirty from all the writing and erasing. Wrinkly papers occupy his desk and parts of the floors, scribbled with future projects and intricately drawn schematics, some so cartoonish that they were most likely just drawn for fun. It's truly a marvel.

For so long, this room has served as an incubator for his ideas, birthing the countless projects and aspiring prospects in his mission to help the world. Now this room belongs to Hiro. He never thought he'd see this day.

His eyes water again, and this time he does take the tissue that was previously offered to him.

"Tadashi? You okay?"

He wipes away the remaining tears, blowing noisily into his tissue. "I'm just… really proud of you."

"Okay, bro. I'll just… give you a minute—"

"Come here." He pulls Hiro into a crushing, fraternal embrace.

"… Not that I'm not loving this, but we're kinda pressed for time here."

"Just one more minute."

"Okay, that's enough of that." Hiro escapes his air-tight grip. "Stand over by the wall so I can scan you." Tadashi does as he's told and stands with his arms up, letting the teen scan his measurements. Hiro then hooks up his laptop to the 3D printer at the corner of the room. A program appears on the screen, displaying Tadashi's form according to his measurements. Baymax waddles over to his charger, and the lithium-ion battery hums to life as soon as he steps into it. They need him to be fully charged for what's to come. "So I'm thinking something fireproof."

"Sunfire doesn't want to hurt me."

"Yeah, but knowing you, you'll jump headfirst into his flames just to try and save one of us."

"Are your suits even fireproof?"

"Of course. There's only one problem with making yours. Actually, there's a few."

"Like what?"

"Well, with the exception of Fred, everyone's suits are compatible with their scientific specialties, and your interests are so much more… _vague_."

"What does that mean?"

"It means what it means." Tadashi raises a brow. He doesn't know what to make of Hiro's comment; it's not insulting, but it doesn't sound like a compliment. "Don't look at me like that. Your thing is helping people, and there are literally billions of ways you can do that. So I don't know what weapons to give you. I don't even know how to go about designing this thing!" Hiro's head falls onto the keyboard. "We really don't have a lot of time to think about this. I should just recycle Baymax's prototype suit and fashion it into some sort of armor or something…"

"Ahem." The Hamada brothers turn to see the comic book guru leaning against the doorjamb. "I couldn't help overhearing, and I believe I have the solution to your dilemma." With a swagger in his step, Fred hands over a piece of paper.

Hiro and Tadashi balk at its contents. "Did you just draw these?"

"The idea came to me in a dream, actually. The night of Tadashi's return, in fact. Because of his miraculous revival, I knew he would be a valuable member of the team, a secret weapon of sorts, and how right I was! All he needed was the outfit."

"Fred, I don't say this a lot, but I'm so glad that you're a comic book nerd!"

Fred put his hands on his hips haughtily. "It was only a matter of time before you recognized my genius." He then starts humming some song Tadashi doesn't recognize, but he hears something that sounds suspiciously like "Fred's Angels" among the indecipherable hodgepodge of lyrics.

Meanwhile, Hiro immediately gets to work on making Fred's design. As much as he objects to Tadashi becoming a part of the team, he is super excited to make this suit. "Wait till Sunfire gets a hold of you…"

An hour later, Hiro and Fred come out of lab looking rather proud of themselves. The others, who have been busy either making tweaks to their own suits or studying for finals, immediately stop what they're doing. When they say nothing, GoGo snaps her gum impatiently. "Well, where is he?"

Fred and Hiro exchange coy glances before standing aside, allowing their newest member to come into the light for all to see.

The others stare in awe and drop their jaws in unison. Even GoGo looks astonished. Hiro and Fred fist bump. Eliciting any kind of response from GoGo aside from annoyance is an accomplishment in itself.

Tadashi smirks beneath his helmet. "Now let's take down Sunfire, once and for all."

* * *

**A/N: I picked BaoBao's breed for a reason. Korean Jindos are extremely loyal to their owners. I read a story about a woman who moved and she had to leave her Jindo behind. The dog ran for miles to her at her new home. I thought it was so sweet, I had to add him to the story.**

**Just two more chapters and an epilogue to go!**


	18. Chapter 17: The one universal constant

**Big Hero 6: ****The Crossover**

**Chapter 17: The one universal constant**

Hiro stares up at the abandoned warehouse, unimpressed. According to Baymax's scan, this is where Sunfire has decided to set up his secret HQ. Aya and the portal are sure to be somewhere inside, and no doubt Sunfire will be waiting for them. Without further preamble, the team makes their way inside.

The younger Hamada whistles in wonderment as he looks around the interior. "Sunfire must have taken a lot of notes from Yokai. This place is the definition of creepy."

"These warehouses have been abandoned for years," says Honey Lemon. "It'd be easy for anyone to get away with… illicit activities here."

"No kidding," deadpans GoGo. "How many creepy, abandoned warehouses do there have to be before the city finally does something about it?"

"I guess if it ain't broke, don't fix it," says Wasabi. He stops as the rest of the team stares at him. "What? It's not like I agree with his methods!"

"Guys, focus." The deep voice coming from their newest member draws the team back together. The white suit stands out like a sore thumb amidst the drab color scheme of the building. The helmet, which has a voice-distorting feature, adds an intimidating factor to the already daunting, white superhero and emits an air of authority that none of them have ever sensed from Tadashi. "Everybody remember the plan?"

Everyone nods, except for Hiro, who fidgets nervously behind the others. They've gone over the plan a million times, but it doesn't make Hiro hate basically everything about the situation any less. This is exactly what Sunfire wants. Even if they do save Aya, there's no guarantee they'll be able to leave with Tadashi. He has the upper hand. Hiro's insides churn at the thought of losing Tadashi to another supervillain's manipulative devices. Not even the sight of his brother wearing the protective shell of his recently engineered suit brings him comfort anymore.

A hand grips his shoulder, and the younger Hamada jumps at the unexpected contact. The black face of Tadashi's helmet stares down at him. "Hiro, what's wrong?"

He looks in his periphery to make sure the other members of Big Hero 6 can't hear them before breathing in shallowly. "I… I'm not prepared to lose you again."

Tadashi's head turns, as if he's checking to make sure the others aren't paying attention, either, then he removes his helmet. The familiar warmth of his brown eyes soothes the growing unease in his gut. "Hey, I'm not going anywhere."

"But you will have to go… eventually."

Melancholy creases at the corner of his eyes, but it doesn't dampen their congenial sheen. "I know, but it will be my choice, not Sunfire's. I will be here as long as you need me." He holds out his fist. "You with me?"

Hiro smirks. "Yeah." They do their traditional fist bump, wiggly their fingers to pantomime an explosion. "Let's do this."

Regrouping with the others, Tadashi leads them through the hall until they reach an office. Through the windows they see the main factory line below. Most of the old equipment has been removed to make room for the equipment stolen from Krei Tech and Yoshida Industries.

"How did Sunfire manage to steal all of those machines without getting caught?" inquires Honey Lemon, befuddled.

"He must have taken them apart and built them from scratch."

"This guy is unreal," says Fred.

"Agreed," says Wasabi.

Behind the portal, Sunfire tinkers with a device that looks suspiciously familiar to the young boy genius. Recognizing the intricate design and engineering, Hiro looks to his older brother. From the look on his face, he must have also realized what Sunfire has built.

"Tadashi, do you see what I see?"

The white hero nods affirmatively. "Parallel beamlines, alignment targets, hydrogen canisters."

"And a superconducting magnet. That's a hadron collider."

Everyone except Fred gapes at them. Wasabi is the first to voice his perplexity. "That's way too small to be a hadron collider. How's that even possible?"

"He must have taken the components from Yoshida Labs. I'm guessing that was their 'secret project'."

Honey Lemon pipes up in excitement, "Oh! That explains the hydrogen canisters. The particles are small enough to accommodate a compact hadron collider."

"And the plasma from of the hydrogen atoms gives it more than enough power to keep the portal stable," adds Wasabi.

"Not to mention the particles accelerate five hundred times faster than a large hadron collider," inputs GoGo. "With that kind of power, he can run this thing for months at a time."

Tadashi hums intriguingly. "So that's how Sunfire got the portal to work."

"I didn't understand anything you guys just said, but even I know that's badass!" quips Fred. "This guy is officially an evil genius!"

Suddenly, Honey Lemon squeals, forcing most of the team to cover their ears. "Do you guys know what this means? This changes quantum physics altogether! Imagine the possibilities—"

"Yeah, it's real fascinating," interrupts GoGo. "Now let's stop him before he can use it."

Tadashi is practically glued to the window as his eyes scour the factory floor. "Does anyone see Aya?"

Honey Lemon points to the right. "Over there!"

Sure enough, the nurse is in the corner, sitting on a cardboard box. The discarded scrap metal that imprisons her is lopsided, like it was melded together haphazardly. She looks unharmed and extremely bored.

"Alright. Let's do this." Everyone parts ways to take up their positions in preparation of their plan. Only the Hamada brothers have stayed behind in the decrepit office, both hesitant to leave the other. Hiro shifts nervously next to Tadashi. "I'm heading out to meet with Baymax. See you on the other side, I guess."

"I'll be fine, Hiro."

The brothers exchange heartfelt smiles. Hiro swallows a dry lump in his throat. If he looks away, he might not see Tadashi again… But he promised he wouldn't go, and the reminder hardens his resolve. "Good luck." Hiro runs off to join Baymax.

Once outside, he wordlessly attaches his magnetic cuffs to the back of Baymax's suit. "Do not worry, Hiro. Tadashi will be safe."

Hiro doesn't respond. No amount of reassurance will help him relax. He tries to focus on the task ahead, suppressing the urge to jump back inside and stop Tadashi before he can initiate the plan. He can do this. They both can do this.

They linger outside the double doors that lead into the warehouse. With bated breath, Hiro impatiently waits for Tadashi to give the cue for them to bombard Sunfire.

"_Now!_"

"That's our cue! Go Baymax!"

Before the beast of a robot can move, they're suddenly surrounded by black figures with kabuki masks. In unison, the Sunfire clones hold their fists up, projecting an amalgamated fire blast at the superheroes.

**O—O**

Aya sits on a cardboard box, completely bored out of her mind. When she first woke up from her chloroform nap, she found herself inside a giant steel cage full of useless junk. Everything was dark and bleak, and it smelled like old motor oil. She gathered from the empty crates and the hooks on the ceiling that Sunfire had set up his whole operation in one of the abandoned warehouses in downtown San Fransokyo.

Her first thought was to escape, but there is nothing within her reach that can help her do that. The prison Sunfire had fashioned from the leftover scrap metal would be nothing for someone with superpowers or at least a kick-ass super suit, but she has none of those things. Even if she did, Sunfire has his eyes on her at all times, so there's nothing she can do that he can't stop himself. Threatening him is pointless. If she even sneezes wrong, Sunfire could just melt her. So she resorts to just sitting around, waiting for Big Hero 6 to come save the day.

This has to be the most boring hostage situation she's ever been a part of—not that she has a frame of reference.

For a supervillain, Sunfire is pretty lowbrow. He's nothing like the villains in the movies; he doesn't cackle, or monologue, or brag about his fiendish plans in order to bring out fear and panic in his captive. Instead, he just silently flies around the room preparing for Tadashi's arrival so he can finish his mysterious experiment and making tweaks to the portal and the machine connected to it. He doesn't even mumble to himself while he's prepping. Can't he at least throw her a bone and do the evil finger-tapping thing? Nope.

Seriously, what do nerds see in this nonsense?

Aya wishes her phone hadn't fallen out of her pocket after he drugged her. She might not have gotten any reception, but at least she would have been able to distract herself from this bleak situation with the games downloaded on her phone. She wonders if BaoBao is safe. Korean Jindos aren't known for sitting still while their owners are missing. She wants to believe that he somehow found Tadashi and the others on his own, and she laughs, imagining them suiting up her four-legged companion for battle, complete with helmet and wings. Maybe she'll ask Hiro to design something like that for him. BaoBao would look so adorable, and the kids at the hospital would love it—

Something shifts between the boxes in the corner, breaking her from her whimsical thoughts. For a second, she believes it's BaoBao, but a moment later, a tiny mouse scurries up to her, blinking up at her innocently. "Hey, little guy. You wouldn't happen to know a way out, would you?" Instead of answering, the mouse scurries off and makes its merry way through the bars. "That's very helpful, thanks."

"Sunfire! I'm here for my friend!"

Aya jumps up from the box. Here comes Big Hero 6 to the rescue! She runs up to the bars and grips them in anticipation. She gets as close as she can so she can watch the exchange between Sunfire and… the stranger who has suddenly shown up inside the factory.

The stranger is covered head to toe in white carbon fiber armor with a red trim. Underneath the plating is a black Kevlar that covers his exposed hands, elbows, neck, and inner thighs. The black visor on the white and red helmet covers the stranger's face. She doesn't recognize who it is at all. He claimed to be her friend, but he doesn't resemble any of the members of Big Hero 6. Maybe it's another superhero she's never heard of…?

Whether she knows them or not, the stranger looks confidently supreme standing at the top of a staircase leading to an office, thanks to the masterpiece of robotics and engineering that is his superhero guise. Even though she can't see his face, the mystery of the helmet as well as the aesthetically pleasing design of the suit makes him look… _charming_. Like a knight in shining armor.

Now she's starting to understand the appeal of superheroes.

"So, you have come," says Sunfire. "And it looks like you're prepared to fight. Are you sure you don't want to do this the easy way, Tadashi Hamada?"

… Did she hear that right? That's what Sunfire said, but it can't be—

"Tadashi?"

The white superhero turns to her. A distorted voice comes out from behind the helmet. "Hey, Aya."

"Our deal still stands, Tadashi."

Tadashi doesn't bow down. "You broke that deal when you kidnapped my friend."

"As you can see, she is completely unharmed. But she won't remain that way for long." Without looking, Sunfire throws a fireball at her cage, scorching the corner where she was previously standing.

"Aya!"

"I'm okay!" Her hair is standing on end, but the blast didn't even backfire.

"Make your choice, Tadashi Hamada."

His helmet moves back and forth from her to Sunfire. "I say… _Now!_"

All of a sudden, a yellow disc flies towards the fiery supervillain's head. He ducks before it can hit him. A yellow streak passes him and stops next to Tadashi. GoGo pops her gum as she holds up her arm, and the disc comes back, attaching itself to her wrist. "Yo."

"The magnetics expert. Where's the rest of your team?"

"Wouldn't you like to know?" GoGo throws the disc at him again. This time, Sunfire flies up only to be hit with a spontaneous fire blast. Tadashi's hand is up, steam lingering from his palm.

Even with the mask covering half his eyes, Aya can tell he looks impressed. "You've learned some new tricks." A nefarious smirk tugs at his lips, the first sign of emotion she's seen him display. "So have I."

All of a sudden, something grabs GoGo from behind, attaching her to the wall adjacent to Aya's cage. A figure that looks exactly like Sunfire appears next to her, holding up its hand as the yellow hero is met with resistance.

"GoGo!" Tadashi runs to her, only to be dragged away in the corner, out of Aya's sight.

Oh God. There's more than one.

"_Psst! Aya!_"

Aya's neck twists so fast she nearly gets whiplash. The disembodied voice doesn't help with her nerves. "Who's there?" she demands.

"It's me, Wasabi!" the voice hisses. Her eyes scan the boxes until they settle on a pair of brown eyes behind a pair of transparent green visors. "I'm gonna get you out." Wasabi lifts up pair of lucid knives that crackle with amorphous energy. He slices through the bars in three swipes, filling her cage with an acidic stench that burns the inside of her nostrils.

He holds his hand out to her, but before she can reach it, another figure creeps up behind him. "Look out!"

The Sunfire doppelganger slices the top of her prison clean off with its extremely hot and serrated arms. Wasabi faces it head on, albeit feebly. "G-Get back!" It tilts its head before engaging the large black man. When he does nothing but hold his arms in defense, Aya closes her eyes so she doesn't have to witness Wasabi's decapitation. After a few seconds, she peeks one eye open to see that Wasabi is still whole and the fake Sunfire without any arms. But Wasabi doesn't let his guard down. In a matter of seconds, the arms grow back, and they glow blazing blue instead of scorching red. A gust of flames hits it from behind, where Fred's monstrous form stands triumphantly.

"Aya, go!"

She runs, heading for the closest exit. "Did you really think I didn't notice you?" From above, another Sunfire grips her by the collar of her hoodie.

"Let me go!"

He raises his other hand above his head, ready to take aim and disintegrate her when, out of the blue, a ball falls on the Sunfire, dousing him and his fireball. Aya looks up and spots something pink perched on the rafters above. She looks back at Sunfire, who remains in the air, unchanged. "It's useless. My suit can heat up to over one million degrees Fahrenheit." He holds out his hand to make another fireball, but nothing happens. Suddenly, the villain is incased in a milky-white film that makes his movements staggeringly slow. Aya shirks her jacket and falls gracelessly to the floor while he sinks down, landing on his feet as agilely as a cat before freezing completely.

The pink figure drops from the ceiling via a stretchy, gelatinous substance that reminds Aya of silly putty. She immediately recognizes the tall, lanky form of Honey Lemon. "Are you okay?"

"Yeah, I'm good." Aya pokes the Sunfire's frozen form precariously. "How'd you do this?"

The pink hero blushes. "Oh, it was nothing. I just used a little water, some α-cyclodextrin, and mixed them both with 4-methylpyridine. Once the chemicals become superheated, they create a solid that's as impenetrable as diamond."

"I didn't understand any of that, but it's still impressive."

The girls duck as several more Sunfire doppelgangers burst through the factory doors and into the parallel wall and are smashed to bits by a giant red fist. A moment later, Baymax flies in, covered in scorch marks. Hiro jumps off his back, brushing the soot off the visor of his helmet. "You guys okay?"

"I don't know how to answer that question," says Aya. "Have I gone completely crazy, or has there always been more than one Sunfire?"

"They're microbots." Hiro holds up a black piece of technology Aya doesn't recognize. It twitches before powering down completely. "Sunfire didn't just take notes from Yokai. He stole the whole book. He must have found my microbots somehow. That's how he was able to steal the portal and how he got away with the plasma canisters without getting caught."

"How is he controlling so many at once like this?" Honey queries fretfully.

Aya backtracks to the first part of Hiro's revelation. "These are _your_ machines?"

"I got rid of them long ago so no one could ever use them like this again. Apparently, I wasn't too thorough."

"So you know how to stop them?"

"We have to find the neurotransmitter that's controlling them." Hiro opens a compartment on his wrist, pressing a button. "Can everyone hear me?" He receives various replies from the rest of the team. "They're microbots! One of these Sunfires is carrying a neurotransmitter behind his mask!"

"_Again? Seriously?!_" Aya hears the exasperated cry of Wasabi.

"_Awesome!_" Fred's blue and orange monster suit zips over them and through the double doors, scaring the crap out of Aya.

"_I don't think… it's that simple!_" GoGo's voice sounds strained. "_These Sunfires are extremely stable for just being hunks of microbot! This one's using my own abilities against me!_"

"_Mine too!_" cries Wasabi.

"But that doesn't make sense," says Honey. "Sunfire only fought GoGo and Fred. He doesn't know about the rest of our abilities."

Hiro's eyes widen in realization. "… Until now. The microbots are adapting. Somehow, Sunfire modified them to take on any opponent they face. Which means he's probably not using a neurotransmitter at all."

"And now he has even more of an upper hand."

Aya does not like the sound of this. "So what now?"

Before anyone can even blink, the three are roughly pushed against the wall by another Sunfire. It melts into his original malleable form, adhering them to the wall like an industrial adhesive. Beside them are the rest of the fallen team. The original Sunfire flies up to them. "I tire of this game…" Holding up both hands, Sunfire drifts closer as he prepares to end the lives of Big Hero 6, as well as the innocent bystander who unfortunately became a part of all this.

"I know this doesn't mean much now," Aya speaks suddenly, "but thanks for coming to save me."

"No prob," replies Hiro with no amount of irony.

GoGo pops her gum. "Seriously, guys?"

"Humor is often used as coping mechanism when one is in mortal peril," Baymax randomly states.

"Enjoy these last moments while you can, heroes," Sunfire interrupts. "Because this is the end for you all."

"Think again, Sunfire!"

The whir of a machine turning on hushes the group. Sunfire turns and the rest of them gaze in awe and trepidation at the activated portal, where Tadashi is standing. The wormhole opens up, spiraling with a foreign energy that makes Aya shudder. Tadashi presses another button, and all of a sudden the wormhole turns into a vacuum.

"Tadashi, what are you doing!" Hiro shouts over the gradually growing current of the wormhole's vacuum.

"Ending this once and for all!" The white hero turns to the villain. "You want me, come and get me!"

"Tadashi, don't!" Aya and the others cry out desperately for their friend, but the damage has been done. Without another word, Sunfire flies at the foolishly brave young hero, and both disappear into the wormhole.

"_Tadashi, NO!_"

Shortly afterwards, the wormhole closes, and the portal shuts down. Simultaneously, the modified microbots fall to the floor, releasing them all from their vice-like grip.

Hiro runs over to the computers and starts jamming buttons, but they don't turn on. "Why isn't it working?"

Honey Lemon gasps in realization. "The collider!"

"What about it, Honey Lemon?" he snaps impatiently.

"The particle beams were supposed to stabilize the portal as soon as it turned on, and it needs the superconducting coils to concentrate the direction of particle beams, but…"

Aya follows her gaze, confused. Her confusion is quickly dispelled when she sees what the problem is. She may not be a physics expert, but she's done enough research know what a superconducting magnet looks like. The protective shell of the magnet was pried open by someone who obviously knew what they were doing, and the iron yoke covering the magnetic dermis looks as if it was punctured by a laser until it hit the center, where the remnants of the superconducting coils are scorched and gnarled beyond functionality.

She sighs in resignation. "That idiot…" Tadashi knew it would come to this. He must have used the chaos of the battle as an opportunity to compromise the portal and trap Sunfire. And Sunfire knew it, too. That's why he didn't bother to waste any more time on them when Tadashi basically handed himself over on a silver platter; that's why Tadashi wasn't among the rest of them when they were all trapped against the wall; and that's why, even though he had the power to stop Tadashi, he didn't.

And now they all know it, too.

Well, not all of them. "We have to get him back!"

"Hiro, there's nothing we can do."

Hiro ignores GoGo and continues to type into the computer. The others watch him struggle, heartbroken by the abrupt loss of their friend and their inability to help him. Aya looks in trepidation as Hiro practically bangs his gloved fingers on the keys, his breath growing more ragged by the second.

When he starts punching the keyboard, she finally intervenes. "Hiro, that's enough!" Aya grabs his hands and holds them firmly as he struggles.

"He promised! He promised he wouldn't leave!"

"Then he'll come back!" The conviction in her voice surprises even her. Aya has only known Tadashi for three days, but anyone could see just by looking at him that he is extremely, obstinately loyal. He'd return; not even an interdimensional wormhole will stop him. "If he promised you he'd be back, then we have to trust him." Teary-eyed and stuffy-nosed, Hiro nods and faces the portal, his gloved hand still in Aya's steadfast grip.

The others join their side, and together, they wait for their friend to return to them.

**O—O**

The vacuum of the wormhole brings about a familiarity that Tadashi did not miss. The sensation he felt his first time inside this dimension—the fear of never going home, the calm that came immediately afterwards, the panic when he reached for his hat only to find that it wasn't there—envelops his brain in a nauseating wave. Dazzling colors cloud his vision once more, rousing his gag reflex.

Tadashi closes his eyes, fighting the urge to vomit. He refuses to throw up in another dimension. When the nausea goes away, he opens his eyes. He's astounded by the paradoxical faculties of this dimension. While it does act like a vacuum, the air is plentiful and sound can still travel, as proven by the echoing guffaws he can hear in the distance. Callaghan was right; there's still so much to learn about this dimension.

As the low chuckling comes closer, he turns and spots a black figure a few meters away. Sunfire floats closer to him until they're face to face. "You're smarter than I gave you credit for, Tadashi. Well done." Sunfire's voice infiltrates his ears once more, and it takes a moment for Tadashi to realize that he must have highjacked the comm link in his helmet. The fiery villain looks as if he's already grown comfortable with the weightlessness of this dimension. "Now what?"

"Now, you answer my questions."

If there's one word Tadashi would use to describe Sunfire, it's tactical. The supervillain is a superb strategist, someone who thinks three steps ahead. The only feasible way to defeat him is to out-think him, but the time limit that the arsonist set gave them very little wiggle room to think that far ahead let alone that quickly. So Tadashi hatched a plan of his own. If he couldn't stop Sunfire, then the next best thing would be to turn his own trap against him. Unfortunately, this required actually falling into his trap without a backup plan. Hiro and the others never would have gone along with this if they knew about it, and if he makes it out of this alive he's sure to get an earful and a few well-deserved slugs. But it had to be done.

Now he can finally settle this. No more running. No more hiding.

"Go ahead then. Ask your questions." Sunfire leans back as if he's reclining, crossing his legs and folding arms behind his head. "We're going to be here for a while."

"You don't seem too concerned about getting out of here. Why aren't you trying to make me use my powers so we can go back?"

Sunfire laughs out loud. "You think I can control you in here? If I could, I wouldn't have even needed you in the first place."

"Why do you need me? Why did you reconstruct the portal and build a hadron collider? What was the point of all of this?"

Erecting himself from his lax position, Sunfire drifts closer to Tadashi until they're face to face. Well, mask to mask. "I want to explore the realm of impossibility."

"… What does that even mean?"

"It means exactly what it sounds like. Your very existence is a scientific marvel, something that's only ever been accomplished in science fiction. Your powers are evidence that the multiverse theory is true. You can travel to any time in any place in any universe. You can change reality as we know."

"You mean _you_ can. I never wanted these powers, but you deserve them even less. I would never use them to change the world like that."

Sunfire opens his mouth as if to respond, but it closes and sets back into a thin-lipped line that makes him hard to read. "No, I suppose you wouldn't."

Tadashi observes Sunfire quizzically. His explanations so far have been sound, but the way he's talking about traversing the boundaries of time and space, it sounds so… superficial, like a rehearsed line.

"Shouldn't you be you angry that I ruined your plans?" Sunfire's silence answers his question. "Unless this was part of your plan. You knew I was going to disrupt the particle beam. You _let_ me trap us here." Now that he thinks about it, his impromptu plan worked almost _too_ well. In fact, Sunfire didn't even seem to try to subdue Tadashi at all. "During the fight, you barely made any effort to combat me. You basically ignored me."

"My intention was never to hurt you."

"… I don't think you're a villain. You may look the part, you may even act like it, but you're not evil. If you really didn't care you wouldn't have hesitated to end the lives of my friends. But you didn't."

"I was about to—"

"No, you weren't, and we both know it."

"… You were always the more perceptive one, Tadashi."

The weight of his words gives Tadashi pause. The guilt in his voice is more tangible than the very dimension they're floating in. No villain can express such remorse. "Who are you? Really?"

The masked arsonist bites his lip, the first sign of hesitation he's ever shown. Slowly, he reaches up to the mask, removing it and the elastic hood of his fire suit. And in that moment, Tadashi's heart stops.

Once again, he's back in that moment, his first encounter with Sunfire. Without the suit and the mask, he appears more innocuous than his supervillain persona. As the mask-less stranger approaches him, the fuzzy image of his face starts to clear up until he's met by the most unanticipated sight…

He remembers now. He didn't summon the portal because he was scared of the villain. He was startled, startled by revelation of the true identity of Sunfire.

"H… Hiro?"

Sunfire shoots him the same venomous look he directed at him when Tadashi first used his real name. "So you remember. Sorry to disappoint you again, but the boy you once knew no longer exists. Then again, you and I don't truly know each other, do we?"

The young man before him definitely isn't the young, mischievous boy that Tadashi grew up with, but the longer he stares at this stranger, the more he can make out his little brother's physical qualities: his clever brown eyes, his unruly raven hair, even his buck teeth. But years of brutal determination and tired endurance painted on his visage makes the young man seem several years older than he should be, and the bright, inquisitive glimmer that is cognizant of his younger brother seems to have disappeared a long time ago.

"I-I don't—Why would—How did you… What happened to you?"

The bags under Hiro's eyes sink in despondence. His jaw clenches in unbridled rage. "Six years ago in my universe, I lost my parents to a chemical fire. It was an accident that never should have been, and I knew there was only one way to prevent it from happening."

Tadashi's eyes widen even further. "You were going to go back in time just to save our parents?"

"You think me foolish, but I have already proven that it's a possible feat. I left everything behind to build a portal capable of opening traversable wormholes." Tadashi expects no less from his genius brother. He always knew that Hiro could accomplish anything he put his mind to. But he never thought he'd use his talents to do something like this.

"When I first went into the portal, I had miscalculated one of the spacetime equations, and instead of going back in time, I ended up in another world. Luckily I landed in the lab of a billionaire who possessed the same portal I built in my world. All I needed was the hadron collider, and you, apparently."

"I didn't plan on using you at first. I can only imagine how you ended up inside the other dimension, and we both needed to leave before we disrupted the balance of the universe. But the implications of your presence meant one thing: Everett's phone. With you, I could go back in time, save my family, and with the knowledge I've obtained, I would be the first to accomplish interdimensional travel. I would be a legend—a god amongst men!"

"That doesn't sound like Hiro."

"Don't pretend like you know me!" His voice fills with vitriol, making Tadashi flinch. He grips his mask so tight it cracks. "You're not the Tadashi from my world. That Tadashi was never there for me after the fire. No one was. Aunt Cass was too distraught to even take care of us, and when I told _him_ about my idea, he called me crazy and wanted nothing to do with me."

"Which explains why you didn't simply just ask for my help. But why the fire suit?"

"It was going to take me at least a week to reconstruct the time machine, and it was only a matter of time before Krei went behind my back and called for help. So when I discovered there were so called 'superheroes' in this universe, I decided to play the part and became a supervillain. I built this suit and took on the name Sunfire so I would _never_ forget what I lost."

It breaks Tadashi heart that his little brother put himself through so many extremes just to restore the family he lost. He became this person because his Tadashi abandoned him, but the white hero can't believe he would do such a thing in any reality. Is this what his Hiro would have been like if he gave up on him? Would the superhero Hiro be this bitter and isolated without his friends?

Suddenly, the alternate Hiro grasps him by the shoulders, and Tadashi is put off by the manic look in his eyes. Right now, he's looking at Sunfire, not Hiro. "You can still help me, Tadashi. All you have to do is send me back, and then we can part ways. You and your friends never have to see me ever again, and you can return to your own world."

"I wouldn't even know how to go about doing that. Opening wormholes is one thing, but controlling the point in time…" The crazed countenance that possessed his brother sinks into despair, and Tadashi's heartbreak increases tenfold.

He understands what this Hiro is going through. He was around the same age when he lost his parents. Hiro was only three, and Aunt Cass could barely function the first few weeks they were in her custody. He'd never felt so alone and miserable in his life. But he got through it. As long as he still had Hiro and Cass, he could get through anything. But this Hiro didn't have that luxury. He gave up his family, his friends, everyone and everything that mattered, to get to this point, and now it seems he's finally lost it all. The faux villain's hands sluggishly slide of his shoulder and he practically shrinks into himself. For the first time, Tadashi watches defeat overcome his brilliant little brother.

In that moment, Tadashi makes a decision. Removing his helmet, he looks Hiro straight in the eye. "I may not be your Tadashi, but I still care about you, Hiro. And I'm not giving up on you."

Grabbing the mask from his limp grasp, Tadashi concentrates. He focuses on the location in his mind, mentally summoning the cosmic energy of the dimension. His head feels like it's about to burst, but he perseveres. Just when he's about to reach his limit, colors burst to the surface of his mind—reds, blues, greens, pinks—every color that's ever existed and or could ever exist unleashes in a variegated wave of enlightenment—

And just like that, the drill of pain stops. The energy that was blocked unleashes, pacifying the throb in his temples. It travels done his neck, through his arms, and into his fingertips, soothing his body like a celestial cascade of interdimensional ambrosia. A portal manifests before his eyes, and on the other side he sees the Lucky Cat Café standing in all its feline glory.

"I did it…" He laughs in disbelief. After days of a piercing migraines and relentless nausea, he finally masters his new abilities. And all he had to do was stop thinking in order to see the bigger picture. He'll never doubt Hiro ever again. "I did it!" He whoops and hollers, wiggling his body in a way that almost seems like dancing but mostly bears resemblance to a twisting worm. "Yes!"

"That's…" Tadashi pauses his celebratory jig. Hiro drifts closer to the portal, his black hands hovering over the image. Inside the café, a woman sweeps around the tables and chairs. As she exits the café, a group of familiar-looking people approaches her. She welcomes them warmly, exchanging hugs and kisses before gesturing for them to enter her establishment. "This is my world. How'd you…?"

"It's best you don't think about it."

The arsonist clenches his jaw, much like his Hiro does whenever he's not given all the details. Apparently, it's a universal rule for Hiro to pursue knowledge that will forever be beyond his grasp. "I don't understand. This is the time when I left."

"Yeah, it is."

"… I can't go back there."

"Look." Tadashi grips both his shoulders, meeting his gaze with strong conviction. He needs Hiro to understand—he _has_ to. "I know you. You may think I don't just because you're from an alternate world, but I've dealt with this stuff long enough to know that no matter where you're from, all Hiros are pretty much the same, and so am I. And if I know me, then I know that your Tadashi would never intentionally hurt you or abandon you in your time of need. Yelling at you was probably just his way of dealing with your parents' deaths. If anything, your leaving probably hurt him even more. Trust me, he misses you."

Sunfire eyes scrutinize the image in the portal in confliction. The woman is now sitting at a table with her guests, laughing and sipping from a mug shaped like a cat. "How can you be sure?"

"Because it's a law that all Tadashis in all existing universes will always be proud of their Hiros, not matter what. I'm calling it 'The Universal Law of Hamada'."

For a second, Tadashi sees his younger brother in the desolate eyes of this angst-ridden young man. He still doesn't look convinced, but Tadashi is confident enough to let him go. "I think… this is a terrible idea."

"Of course."

"And I'm giving up on time travel."

"I wouldn't expect you to."

Hiro raises a skeptical brow, as if he expects Tadashi to give him another lecture. "You're definitely not my Tadashi. In fact, you're not like anyone I've ever met. I don't know how this dimension works; this realm of science is still a mystery even in my universe. But whatever science, magic, or higher power that may be bestowed these abilities upon you for a reason… and I can't think of a better Tadashi who deserves them."

And with that final word, Sunfire goes through the portal. Tadashi leaves it open for a moment to watch. Sunfire doesn't immediately enter the café, but he doesn't run away, either. And if he knows Hiro (and by this point it's been undeniably established as a universal rule that he knows any and all versions of Hiro that may or may not be), he'll come around soon enough.

"Okay. Now, it's my turn." Cracking his fingers, Tadashi summons the cosmic energy within himself and opens a portal back to the other world. On the other side, he sees all his friends standing in front of the portal. They all look ready for him to appear any minute, no one more so than Hiro and Aya. At some point, the teen took off his helmet, so Tadashi can see that his cheeks are painted with twin streaks of salty tears. Aya looks more composed, but the hand that isn't holding Hiro's trembles against her chest.

Boy, will they be surprised.

**O—O**

He looks at up at the giant cat waving at him. Its welcoming smile brings about a nostalgia that makes his chest ache. Looking inside the café, he observes the familiar faces he left years ago, faces he never thought he'd ever see again. Watching their jubilance as they exchange stories, joke around, and enjoy each other's company, the emptiness he felt in his heart for ten years corrodes into a wider hole full of sorrow and regret.

This was a mistake.

As he turns to walk away, something stops him in his tracks: a little girl around three-years-old, holding a white doll with beady eyes, staring up at him with childlike wonder. "You lost, kid?" She brings a thumb to her mouth in response. He kneels down so they're eye to eye. "Where are your parents?" She continues to stare, blinking owlishly. Didn't her parents ever teach her about stranger danger?

"Maemi!" A woman in her late twenties runs up to them. She picks the little girl up, hugging her tightly and softly scolding her. Problem solved, he starts walking away from the café.

"Hiro?"

That voice. It's been so long since he's heard that voice. Turning back around, he nearly forgets to breathe. It feels like he's confronting a ghost from his past. The man is dressed in a beige cardigan, black slacks, and a polished pair of cap-toe oxfords. His raven hair is combed back neatly, and his chocolate brown eyes gawk at him behind a pair of metal-rimmed glasses. His left hand, which is holding a black blazer, possesses a wedding ring. "Tadashi?"

The well-groomed man takes a wary step, then another, and another, until finally, he reaches out and roughly pulls him into an intimate embrace. Tadashi shakes against him, overwhelmed with emotion. His voice quakes in his ear. "I-I thought I'd never see you again. I've missed you so much…"

The hole in his heart fills with the memorable warmth and security that he's missed for so long. His arms encircle his older brother, clinging to him for dear life. "I missed you, too."

The brothers clasp each other as closely as they possibly can, reconciling ten years of lost love, before releasing each other, wiping away unmanly tears. Tadashi laughs as he gets a good look of his younger brother. "Bro, what are you wearing?"

"It's… a long story."

"Well, we have plenty of time to catch up." Tadashi puts his arms around him, leading him towards the café's doors, where the woman and the little girl are still waiting.

Later that night, as he reacquaints himself with his friends and his new family, Hiro thinks of the other Tadashi and his eponymous universal law. The wonders of the universe, the secrets of time travel, the physics of the spacetime equations that allowed him to find other worlds—none of that matters because the everlasting love he and his brother share will always be constant.

* * *

**Just one more chapter and an epilogue to go!**


	19. Chapter 18: Miss me?

**Big Hero 6: ****The Crossover**

**Chapter 18: Miss me?**

"Here we are! Home sweet hotel room!" Cass moves aside with a flourish to let Tadashi into her temporary living quarters.

He closes the door, ogling the giant screen TV perched on the cherry wood dresser across from the bed. "This place sure is ritzy. Can you afford to stay here while the café is under construction?"

A devious smirk slides onto the older woman's face. "I have a few weeks' worth of hotel vouchers I've been saving up over the years. I think I'll be alright."

"And they just let you keep Mochi here?"

"Of course!" A meow rumbles from under the queen-sized bed. "You can come out now, Mochi. It's just Tadashi." The pudgy calico squeezes him out from under the bed and jumps on it, pawing at the freshly cleaned sheets.

"Why do I get the feeling you've done this before?"

"Well sometimes when I visited your dad at school, I couldn't always find a sitter for my furry companions. But that's a story for another day." Crossing the room, Cass plops down onto the bed. Mochi crawls onto her lap, purring up a storm. She pats the spot next to her. "Sit."

The young man lingers at the door a little longer. This talk has been a long time coming. He's been trying to figure out what to say to her these past few days, but he knows nothing he'll say will make the truth sound any less like the crazy adventures in Fred's vintage comic books.

It's been three days since Tadashi sent Sunfire back to his original world and finally mastered his interdimensional powers. Just as he predicted, as soon as he ported back into this world, he was immediately welcomed with lectures and violence. After GoGo and Aya had their fill, the others finally pulled him into a group hug. Hiro hadn't let him out of his sight (the others practically had to drag the teen to school today so he wouldn't miss finals) and Aya stayed by his side to, in her words, "monitor his condition in case his time in the dimension gave him any other weird cosmic powers." After two days, there was no sign of any side effects, and Tadashi was declared normal. But that didn't stop his friends from watching his every move. Visiting Cass is a much-needed reprieve from their overbearing concern.

But now that he's here, Tadashi considers just walking back out the door and avoiding the impending discussion altogether. The stern look Cass gives makes him rescind that thought. He sighs in defeat and takes the spot on her left. Mochi leaps onto his lap, demanding attention. Tadashi scratches his chin absentmindedly.

"I'm sorry I didn't visit you while you were in the hospital."

Cass waves her hand dismissively, giving him a nice view of her stitches. The jagged sutures weaved into her flesh make him wince impulsively. "Oh, I'm not mad about that. I'm just glad you're okay. But I would like to know why you ran off and left me after we just escaped a burning building. And while you're at it, you can explain to me how you survived the fire at the showcase three months ago."

Tadashi coughs nervously. "You may not believe me."

"Try me."

"Are you sure? It's really unbelievable."

"As unbelievable as a bunch of college students becoming superheroes?"

His eyes nearly bulge out of his skull. "You knew?"

Cass scoffs. "You think I wouldn't notice after three months? Hiro may be many things, but he's definitely _not_ subtle. You should have heard the excuses he gave me. 'I have to meet the guys at the San Fransokyo Credit Union for a project!' Who even does that? It doesn't take a science degree to put two and two together."

Tadashi laughs. Hiro has never been good at lying. "So that doesn't… freak you out?"

"Are you kidding me? What aunt wouldn't worry about their only nephew sneaking out at night to fight crime? I would have confronted him, too, but around the same time the heroes showed up, Hiro finally started acting like himself again. He was even socializing with people at school, which wasn't exactly easy for him to do before. Now he's thriving, and it's because of this new, frighteningly hazardous job. As much as it scares me, I know that Hiro knows what he's doing, and I feel a lot better knowing GoGo, Honey, Wasabi, and Fred are looking after him.

"Everything was starting to get back to normal. And then you appear out of the woodwork, and… I don't know how to feel." She holds her hands up apologetically, misinterpreting his melancholic expression as umbrage. "Don't get me wrong, I was really happy that you came back. I was also curious about how you survived, but I didn't want to ruin your homecoming. Then you and Hiro had that fight, and I tried bringing it up again, and then the fire happened, and when you ran away—" Her breath hitches. "—it felt like I was about to lose you all over again."

She collects her breath and looks him pointedly in the eye. "Look, Tadashi. I'm not a scientist. Cooking is pretty much the closest thing to science that I know. I don't understand half the things you and Hiro talk about, and sometimes it makes me feel… powerless, especially when I can't help you. But I will always be here for you, whether it's to lend an ear, or to provide comfort food." She pats his knee encouragingly and adds as an afterthought, "And I won't judge!"

Tadashi puts his hand on top of hers. It's soft and warm, much like her homemade brownies, and it fills him with an aching comfort that he misses dearly. He thinks of his other aunt and all the times she's been there for him and Hiro. All those long talks, all the treats she snuck down to the garage while he was struggling with a school project, all the sing-alongs in the kitchen. He imagines her now, waiting, mourning, clinging to the last strand of hope that her nephew will come back, and he has to catch his own breath. Cass has always been there for him, and he needs to do the same. But first he needs to set things straight with this aunt.

"Okay, Aunt Cass. Just… promise me you won't freak out."

"Like I said, no judgement."

And so Tadashi tells her the truth from the very beginning. Cass doesn't interrupt, and her expression remains neutral, even through the most outlandish parts of the story. He skips the part about discovering Sunfire's true identity—which he hasn't even shared with his friends—and wraps up the story with nice, neat bow. After he finishes recollecting three days' worth of extraordinary events, he gauges her reaction.

"… Wow."

"I don't blame you if you don't believe me."

"No, no. I believe you. If one of my nephews is a superhero, then why can't the other one have superpowers?" Cass averts her eyes, running a hand through her hair as she takes in everything that Tadashi's laid out before her. "Can… can you show me?"

He nods, holding up his hand as a small portal unfolds before them. Cass gasps as she looks at the space where the TV used to be and sticks her hand inside. A hand appears above Mochi, and the disembodied limb startles the feline out of Tadashi's lap.

Cass takes her hand back and stares at it in wonder. "Amazing…" A chortle slips from her lips, and Tadashi is caught off guard as she slings her arms around his neck. "My nephews are amazing!"

"You're taking this much better than the others did."

Cass releases him, her smile ten times brighter. "Oh, I'm still freaking out on the inside, but—oh my gosh! That's incredible! My nephew, the fancy spacetime explorer…!" And just like that, her jollity stops as soon as it starts. "So… so you're really from a different universe?"

"Yeah."

"Which means… you have to leave."

Tadashi nods numbly. He can try to steel himself as much as he wants, but nothing could have prepared him for the inevitable remorse tangling his insides. "I'm sorry."

"Don't be. From what you told me, it sounds like you were doing well before you fell into our world. I'd like to believe that my Tadashi would have turned out the same way, just without the superpowers. So, when do you leave?"

The default ringtone of his disposable phone beeps from his pocket. He checks the caller ID. "I guess I'm leaving now. Aya's waiting for me." He gives the calico an ear scratch before standing from the bed. "See ya, Mochi." He heads to the door, avoiding Cass's gaze. If he looks at her again, he'll start crying. "Do you want to walk me out?"

"Yeah, I'd like that."

As they wait in the elevator, his gaze drifts down to her fidgety hands. They tremble so hard she nearly drops her room key. Keeping his gaze focused solely on the doors, he takes her hand in his. She puts her other one on top. "I don't want to make a scene in the lobby, so I'll just tell you now while we're alone." She squeezes his hand. Her voice, small and feeble as it sounds, makes him feel larger than life. "I'm so proud of you."

Without a moment's hesitation, Tadashi hugs his aunt and lets the tears fall. "Thank you, Aunt Cass."

"And don't tell Hiro that I know he's a superhero."

He snickers. "I won't."

Their tears are gone by the time they reach the lobby. An old sonata sits outside the hotel lobby. A familiar black and tan Korean Jindo sticks his head outside the backseat window, barking excitedly as he sees the two approaching. Aya hushes him quickly from within the vehicle.

"Well, this is it." Tadashi squeezes her hand one last time. "Bye, Aunt Cass. Love you."

"Love you, too!" Before he can open the passenger side door, the crushing grip of Cass's bear hug wraps around his torso. "Last hug."

He returns the embrace, taking in her familiar warm, coffee-coated scent one last time before he returns to his home world. "Last hug."

As the car drives away, Tadashi sees Cass through the rearview mirror. He watches her wave until, finally, she walks back inside the hotel.

**O—O**

"Tadashi and Aya will be here in any minute. Is it ready?" Honey Lemon looks over Hiro's shoulder curiously as the teen concentrates on his work.

"Just a sec…" He types in the last coordinates into the portal's computer. It's taken the team a while to fix what Tadashi had wrecked with his suit's plasma blasters and break Sunfire's codes in order to activate the portal, but after three days of research, Hiro's finally cracked it. At least he hopes so. Pressing another button, the portal hums to life. "Yes! It worked!"

"Yeah, great," says GoGo caustically. "I'm sure Krei will be happy to see that someone finally worked out the kinks for his teleportation device."

After dealing with Sunfire, BH6 retired for a while so they could concentrate on their finals. And because they still needed the particle accelerator and the portal to return Tadashi to his universe, they postponed returning the machines to Krei Tech and Yoshida Labs.

Now, after three days of hard work, they can finally send Tadashi home.

Hiro scoffs at the barb. "It's not like Krei will be able to get it to work again. After we send Tadashi back, the hadron collider is going back to Yoshida Labs."

"Should we really leave it open like this?" asks Honey Lemon charily, referring to the active artificial wormhole.

"Yeah. I don't want to be pulled into the vacuous space of some cosmic dimension," says Fred. "Although, Tadashi _did_ get his powers that way—"

"No." GoGo pulls back the head of his monstrous suit before he can take a single step. "The last thing _you_ need is superpowers."

"I also share Honey Lemon's concerns," Wasabi admits, which surprises no one.

"Don't worry. I went through the calculations ten times, and I replaced the superconducting coils in the hadron collider," Hiro reassures them. "It should be stable."

Baymax, who has been standing silently near the entrance of the warehouse, turns to the superheroes and speaks, "I sense three approaching presences."

"That must be them."

Just as the healthcare robot said, the harried pitter patter of feet running across dirt indicates the arrival of their guests. Predictably, rambunctious BaoBao enters the warehouse first, greeting the members of Big Hero 6 individually with great zeal. Shortly after, Aya comes in, and behind her, Tadashi lingers in the warehouse's entrance. He's currently wearing his suit, and the helmet is grasped under his arm.

His gaze lands on the portal and slowly approaches with considerable caution. "Wow, you actually got it to work again."

Hiro shoots him an offended look, but the smirk he's sporting betrays his resentment. "Of course it works! How dare you question my genius!"

GoGo shoves him halfheartedly. "Hey, 'genius', you weren't the only one working on this thing. You would have failed Doctor Granville's thermodynamics final if we hadn't helped."

Tadashi shares a hearty laugh with his friends as the speed demon ribs his younger brother, who objects firmly that he wouldn't have failed and quietly admits that Wasabi's study guides were immensely helpful.

The sound of approaching footsteps abruptly alerts the group. "Someone's coming!" Honey Lemon cries redundantly.

"Quick, your helmet!" Hiro hisses quietly. Tadashi quickly slips on the white helmet and stands behind his friends. They all agreed that it was vital that Tadashi's identity and his abilities remain secret, so the unexpected arrival of Alistair Krei and his assistant has them all reeling. "What are you doing here, Krei?"

"I've been trying to get in contact with you for days but you haven't been answering my calls. I knew you were up to something and I wanted to find out for myself."

"But how'd you know we'd be _here_?" asks GoGo guardedly.

"I have my ways." Seeing the disbelieving looks sent his way, he quickly confesses. "Okay! I hired someone to tail you guys."

"Not creepy and suspicious at all," mumbles Wasabi.

"Hey, I hired you guys to do a job! You were supposed to find my portal and get rid of Sunfire for me—"

"Who you neglected to tell us about," Honey Lemon points out.

"—and since I don't see that flame-brain anywhere, I assume that you have…" Like a magnet, the billionaire's eyes are immediately drawn to the active portal, and he breaks out into an exultant smile. "Great job, heroes! I knew you could do it. And you even got the portal to work! This is truly…" When he spots BaoBao among the troupe, the ecstatic look on his face turns into disgust. "Whose mutt is this?"

"Mine."

Hiro snickers as the billionaire practically jumps ten feet in the air when Aya appears at his side. Arms crossed, she glares up at him in distain. "Who are you?"

"I'm the team medic, and the 'mutt' is my assistant." BaoBao barks affirmatively from Tadashi's side.

"…Okay then." Krei, who is clearly threatened by the nurse's imposing presence, doesn't question her further and turns to the white stranger in the background. "And who is this?"

"Ah…" Hiro panics, unable to think of an explanation for his brother's presence.

Thankfully, Fred is much more gifted at improvisation. "A fellow hero! He helped us defeat Sunfire and sent him back to the dimension from whence he came!"

Much to their relief, Krei is the gullible type. "A new member, huh? Guess you guys are going to have to change your name from Big Hero 6 to Big Hero 7." He offers his hand to the white hero. "Thanks so much for retrieving my portal, and for getting rid of that pyromaniac!" He squeezes the entrepreneur's hand a little too tightly, making him wince. "Th-That's quite a grip you got there." The whole team struggles to stifle their laughter as Krei tries to recover his hand. Scowling at Tadashi, he straightens his blazer, putting on a professional air. "So, how exactly did you get it to work?" he asks Hiro. He and the others exchange skeptical glances. The last thing they want is for Krei to get a hold of such a powerful and potentially dangerous device.

Suddenly, a thought pops into Hiro's head, and he smirks conspiratorially with the others before facing Krei once again. "Sorry, Krei. That's strictly confidential."

The entrepreneur sputters. "W-What?! But that's _my_ machine!"

"Actually, half of it belongs to Yoshida Labs," says Honey Lemon. "Although, the designs of the portal and hadron collider do look similar."

Hiro walks casually over to the machine, perusing it thoughtfully. "Now that you mention it, they both do bear quite a resemblance. I wonder how interested the CEO of Yoshida Industries would be by this discovery."

Krei is at a loss of words. "Are you accusing me of stealing?"

"Well, it wouldn't be the first time."

"You have no proof!" Krei smirks wickedly. "But _I_ do, and I'm sure you and your friends wouldn't want the CEO of Yoshida Industries to get their hands on _this_ information." Snapping his fingers, he summons his nameless assistant, who hands him a tablet, and with a flourish, he swipes his finger across the screen. He pauses suddenly and then tries again. He spends several more minutes swiping furiously as he searches for the information he has on Hiro and his friends. From the devastated look on his face, he can't seem to find what he's looking for.

Hiro crosses his arms haughtily. "You were saying?"

Krei shoots the teen a baleful look before huffing angrily and traipsing out of the warehouse, his assistant quick on his heels. Once they're both out of sight, the team cheers.

Tadashi removes his helmet, taking in their triumph. "That was awesome! How'd you guys know that would happen?"

"Sunfire deleted all the files on us from the Krei Tech database and Krei's personal computer."

"We weren't sure if he was telling the truth," says Honey Lemon. "We thought he would say anything to get to you."

"So you guys were bluffing," Aya gathered.

"Big time."

"A villain with a heart of a gold. What a plot twist!"

GoGo grins, for once not annoyed by Fred's expository banter. "I have to agree, it was great seeing Krei squirm like that."

"Now we don't have to deal with Krei anymore," says Wasabi, who looks physically relieved by this.

"And to think, it's all thanks to Sunfire," says Hiro. "Even though he was sort of evil, I guess he wasn't such a bad person." He doesn't miss the look Tadashi gives him, but he doesn't comment on it, even when Tadashi's expression surreptitiously switches from wistful sadness and back to the contagious gaiety. The older Hamada brother never did explain what happened between him and Sunfire in the other dimension. He merely said that Sunfire had gone back to where he belonged, and that was the end of that discussion. Whatever happened, it must have been very personal.

The merrymaking stops shortly after as everyone once again faces the open portal. Tadashi heaves a trembling sigh. "So… this is it. I'm going home."

Everyone suddenly falls quiet. The crushing reality of the situation is tangible, and three days ago, Hiro would have been completely heartbroken at the prospect of losing his brother again (for the third time). But today, he's surprisingly calm. In fact, Tadashi's leaving doesn't even bring a tear to his eye. As proven this past week, Tadashi will always be a part of his life, and this brings him closure.

"Oh!" Honey Lemon is the first to break the silence. She nearly knocks Tadashi over as she swings her arms around his neck. "We're going to miss you so much, Tadashi!"

GoGo softly punches his arm. "Don't forget: Woman up." Wasabi grabs her before she can walk away and pulls her into the group hug.

Fred wraps his lanky arms around them all. "Excelsior, true believer."

Tadashi holds out his hand to Hiro and Aya. Hiro takes his hand and squeezes into the group so he can hug his brother, but the nurse stays back. "No thanks. I'll hug you when there's room to breathe."

Suddenly, the whole team is lifted off the ground, courtesy of their plushy, white companion. After he sets them down, Tadashi turns to Baymax mirthfully. "I'm going to miss you, too, big guy."

"Goodbye, Tadashi."

Finally, Tadashi holds his arms out to Aya. She remains adamantly in place. "You promised."

Rolling her eyes, she finally accepts his hug. "You better take care of yourself. And don't do anything stupid."

"Don't worry. If I do anything stupid, I'm sure the Aya in my world will be there to scold me." For the first time since they entered each other's lives, Aya laughs. BaoBao paws his leg, begging to join in on the lovefest, and Tadashi pulls Aya down so he can embrace them both. "I'll never forget you guys."

After breaking the hug, Aya and BaoBao join the others in the sidelines, leaving Tadashi to stand in front of the portal alone. He looks to each one of his friends, each one smiling at him, even GoGo. His gaze reaches Hiro last. The young hero smiles at his brother and nods encouragingly. They can't wait any longer. It's now or never.

In two large bounds, Tadashi Hamada vanishes into the portal. "Good luck, bro."

**O—O**

Hiro types in the last part of the code into the supercomputer and looks up at the portal in anticipation. As expected, the machine remains dormant. The teen bangs the keyboard in aggravation. "Damn it!"

"Hiro! Stop!" GoGo's firm grip stops him before he can get carried away. "You'll break the computer if you keep at it."

"But we're so close!" A frustrated tear threatens to fall, but Hiro holds it back. He refuses to cry in front of his teammates.

It's been three months since Tadashi was sucked into the wormhole. After apprehending Callaghan and saving his daughter, the team started making a name for itself. They became famous throughout all of San Fransokyo and were known as Big Hero 6.

It was a cathartic three months. After making up with Aunt Cass, Hiro was able to see what Tadashi was trying to tell him for the past semester. Now the young prodigy is finally using his genius to help others, he refers to Tadashi's friends as his friends, and he no longer holds any resentment towards Callaghan—thanks largely to Baymax and Tadashi's advice.

Tadashi's disappearance still haunts him to this day, and for the past three months, Hiro hasn't stopped trying to get him back. With the help of his friends, they turned the secret lab into their new headquarters, rebuilt the portal to its formal glory, and even convinced the school to let them borrow the compact hadron collider. However, he still hasn't been able to get the portal itself to work, and the long nights of painstaking research is starting to catch up to him. There's something missing, but what?

If he doesn't figure it out soon, he's going to lose it.

"You should take a break," Honey Lemon suggests kindly. "You've been at this for hours with little rest."

"I can't rest. Not until I figure out the problem."

"Teenagers need approximately nine-and-a-half hours of sleep every night," Baymax comments from somewhere in the background. "Proper rest boosts your immune system, repairs body cells, and helps maintain hormone levels, which is especially important for—"

"Now's not the time for that, Baymax," Wasabi cuts in. "But he's right. At least take a nap."

GoGo grabs his other shoulder, making him meet her eyes. "We're not giving up, Hiro. We'll find Tadashi. But you won't be much help if you can't even see straight."

Despite his best efforts, a stray tear makes its way down his cheek. He doesn't want to stop, not until Tadashi is by his side once again, but he's so tired. "Alright."

He gathers his notes, clumsily picking up papers from the keyboard. His hand accidentally presses a key, and to the immense surprise of the team, the portal comes to life. Hiro gawks at the familiar aperture of the wormhole as it spirals ominously. Gradually, the air in the lab grows thick, and Hiro recognizes the warning signs of the wormhole's vacuum activating, pushing the air around and moving whatever's not bolted to the floor into the ceiling and back around like a funnel. But instead of sucking in the air, it pushes it out, pressing him and the rest of Big Hero 6 into the walls.

"What's going on!?"

Hiro barely makes out the panicked shouts of his teammates. "I think something's coming out!"

The inverse vortex rattles the lab, creating a hurricane. The maelstrom prolongs until, finally, the wormhole collapses in a huge burp, allaying the chaos and destruction it had caused. BH6 falls to the floor, cushioned by their carbon fiber suits, but the effects of the tornado still linger as they all struggle to get up. Hiro waits for the dizziness to dispel before peeling himself from tiled floor. A hand reaches out to help him, and he takes it without thinking. Instead of meeting the familiar face of one of his teammates, he finds himself staring up at the vacuous visor of a stranger.

The mysterious figure is dressed in a white carbon fiber suit with red trimming, swathing the protective Kevlar layer underneath, leaving nothing exposed. The black visor of his helmet is tinted, making his face imperceptible. The design looks familiar, but Hiro can't figure out why. "Who are you?"

In response, the stranger removes his helmet, and it takes the remainder of Hiro's waning strength not to collapse in pure, unadulterated shock. If this is a dream, it's a really cruel one.

As the others collect their bearings, one by one they gasp at the sight before them, their eyes disbelieving. Slowly, Hiro steps closer to the figure. His hands hover over the clean white plating, and fear grips him. He's afraid it's not real, that it's just a figment of his sleep-addled mind and as soon as he touches him, he'll dissolve into illusory dust. But once his fingers graze the solid armor, Hiro collapses into his arms, sobbing noisily. One by one, the other members of Big Hero 6 gather around them, and together, they become one, giant, bawling mess.

"… Did you guys miss me?"

"… Shut up, Tadashi."


	20. Epilogue

**Big Hero 6: ****The Crossover**

**Epilogue**

The warm, delectable aroma of cinnamon and chocolate drifts into Tadashi's nose as he sets up the last table in the Lucky Cat Café, readjusting his SFIT cap. Aunt Cass hums with an extra bounce in her step while she starts up the cappuccino machine. She smiles when she sees her oldest nephew, and he returns it with a mirthful grin of his own. Upstairs, they can both hear Hiro running around, gathering his things last minute because he decided to play videogames the night before instead of preparing for school. When his little brother curses after stubbing his toe, Aunt Cass huffs and asks Tadashi to take the scones out of the oven as soon as they're done before stomping upstairs and scolding her youngest nephew for using profanity under her roof. Tadashi laughs at the argument that ensues immediately afterward.

The teen normally isn't this clumsy in the morning, but Tadashi knows it's only because he's nervous. After all, this will be the first time he attends school without Tadashi. But the boy genius grew up a lot in the three months Tadashi had been absent, and he has faith he'll survive another three months without him by his side. In the meantime, the older Hamada brother will be taking online classes to make up for the work he missed, and his new school gave him an extra few weeks so he can transfer the credits before starting the new semester.

The young man greets his friends as they enter the café one by one. Even though it's a quarter to seven, they're already full of energy. As they conversate, Tadashi spots some subtle differences from their alternate versions: GoGo's cool but kind gaze, Honey's shy smile, Wasabi's slight uniformity, Fred's atypical zest for science and sandwiches. He does the same to Hiro as he trips down the stairs, skimming him from his unruly hair all the way down to his dirty sneakers and back (he can't be sure, but his Hiro might be an inch shorter than the other one).

The distinctions are minimal, but every once and a while Tadashi can't help making comparisons. His world appears no different than the other one, which is the reason behind his fleeting skepticism, but the little subtleties help him remember that this is his one true home. Sometimes he thinks about visiting the other world, but he thinks better of it. He hasn't used his powers since his return, and he doubts he ever will.

But something is still missing…

Shortly after his fall, their aunt joins them all by the door and hands the teen a packed lunch. After ruffling Hiro's hair, which earns him an unconvincing scowl, Tadashi and Cass wish good luck to him and his friends on their first day, but not before they both receive one last hug from the youngest Hamada. Tadashi then flips the sign on the door to the "OPEN" side, signifying to the public that the Lucky Cat Café is officially open for business.

Before the café is hit by the rush of people in need of their morning coffee, Tadashi drags outside a sandwich board displaying the special of the day: The Lucky Catppuccino. He finishes setting up the board, adding a cute drawing of a cat at the top corner when a high-pitched _yap!_ stops him from his task. Two pointy black ears poke up from behind the board followed by another squeaky bark. Tadashi's heart skips a beat at the sight.

Behind the sandwich board is a black and tan Korean Jindo puppy.

"BaoBao?" The canine gives a high-pitched yap in response and Tadashi laughs in elation. "BaoBao!" The dog jumps on him happily, causing his SFIT hat to fly off, but the young man doesn't notice as he's covered in slobbery kisses.

"BaoBao! There you are!"

Tadashi stops laughing, his heartbeat escalating. A few seconds later, a flustered young woman runs up to them. She takes a moment to rest her hands on her knees and catch her breath before she grabs BaoBao's leash. "Bad dog! You know you're not allowed to run off like that! I'm so sorry. Are you okay?"

It takes a moment for him to realize that she's talking to him now, and he quickly gathers his bearings. "Yeah, I'm good. No harm done." BaoBao struggles against the leash as he tries to reach Tadashi, the hat firmly grasped in his mouth. The young man gladly takes it and indulges puppy, letting him lick his hand.

"That's amazing. BaoBao's never this friendly toward strangers."

"What can I say? I have a way with animals." He offers his other hand to the girl. "Tadashi."

She smiles, taking it. "Aya… This might come off as strange, but… have we met? I swear I've seen you somewhere before."

He shrugs, grinning knowingly. "I guess I just have one of those faces."

"Maybe… Hey, can I buy you a coffee, as a proper apology?"

"I'll do you one better. How about I make you a Lucky Catppuccino on the house?"

"I'd like that."

Tadashi opens the door for her, and together they enter the café. Aunt Cass greets her with a complimentary scone, and as Tadashi makes the drink, he watches his aunt and his new friend chat animatedly from his periphery. The familiarity of the scene fills the void that's been present for weeks, making his heart complete.

Finally, things are as they should be.


End file.
